Best portable survival water filters

You know water is vital to emergency preparedness — you can only survive three days without it — and you probably know it can be hard to get consistent and clean water in a SHTF disaster. You can’t depend on “running to the store” at the last minute or carrying all the water you need. Unsafe drinking water causes half of all the occupied hospital beds in the world and over two million preventable deaths each year. Prepare now and avoid the pain later.

We spent 48 hours researching and reviewing over 70 portable survival water filters for preppers so that you don’t have to — and more importantly, so that you don’t buy a bad product and die.

This review covers the kind of products you’d keep in your go-bags, perhaps with some extras in your home supplies or for everyday carry. These products should be one of your very first purchases in prepping.

Reviews: Portable water purification tablets, water canteens and home water filters

Full list of product reviews and details on prepping tips, water risks, etc. are below the table of contents.


  • Water, especially water affected by emergencies like grid failure or flooding, contains organisms that can make you very sick at the worst possible time.
  • Water can be treated in a variety of ways: filter screens, purification chemicals (chlorination), boiling it away and recapturing the steam (distillation), reverse osmosis, UV light, or boiling. Each has its pros and cons.
  • We recommend using filters for basic prepping needs because it’s the best way to quickly turn wild water into drinkable water.
  • You should have at least two of the filters recommended in this guide in each one of your emergency bags. A mix of different types is the best, because no single product is perfect.
  • We recommend keeping 16-24 oz (a normal water bottle) of potable water stored in your bags at all times, that way you have something to drink in the immediate aftermath.
  • Your personal filter choice might come down to whether or not you care about virus protection. Viruses aren’t normally a problem in places like the US and Canada, but could be worse in an emergency or very hot climates. We think about virus protection as a nice-to-have if you can afford it.
  • Companies are in an arms race to have the longest filter life. Giant numbers like 50,000 gallons are under perfect scenarios with clean input water.
  • Capacity matters more when we’re judging numbers like 200 vs. 1,200 gallons. But once the numbers get really high, they start to matter less.
  • There’s no singular perfect mix of products. But do think about how your multiple layers of water treatment products can work together: can you mix and match pieces, do you have vessels for storing clean or dirty water that can attach to your filters, etc.
Our Pick
HydroBlu Versa Inline Filter Kit
Best single product for most people:

HydroBlu Versa Inline Filter Kit

Bacteria/protozoa protection. The kit includes two soft attachable water bags, a hose, hose clamp, and bucket adapter. 0.1 micron filter. Lasts 378,00 liters (100,000 gal). 1.5 oz heavy, 5.5" long.
If you only buy one thing, our top choice for most people is the HydroBlu Versa kit, named so for its versatility. It has a lab-tested 0.1 micron filter that protects you against all the common bacteria and protozoa threats (like giardia and cryptosporidium) and lasts for a massive 378,000 L (100,000 gal). The Versa filter directly competes with the more widely-known Sawyer Mini and Sawyer Squeeze — the filtration quality and lifespan are basically the same, the size is roughly the same (1.5 oz and fits in your closed fist), but the Versa has a noticeably better flow rate that has lead many reviewers to switch from the Mini to the Versa.

We like both the filter itself and this kit because it’s the best bang-for-your-buck. You can use the Versa in almost any possible configuration, such as drinking directly from a water source (like a straw), screwing it onto a standard bottle, or running it inline with a gravity bag or hydration bladder. The Versa is also easy to clean in the field. We appreciate the 28 mm threads on both ends, something almost no other filter offers, so you can attach it directly to most standard water/soda bottles. The kit, which is only $3 more than the filter itself, includes two 64 oz collapsible bags, tubing, and a bucket adapter for gravity setups — making this a cheap DIY gravity kit, too. If your budget is tight, you can buy the filter on its own, then add some 28 mm canteen bags and hoses later.

Upgrade Pick
HydroBlu Go Flow Gravity Kit
Best gravity kit:

HydroBlu Go Flow Gravity Kit

Bacteria/protozoa protection. Gravity kit includes the best-in-class Versa inline filter plus 10 liter bag, hose, hope clamp, and storage pouch. 0.1 micron filter. Lasts 378,00 liters (100,000 gal). 10.8 oz weight.
If you only want to buy one thing but can only spend around $20 more, we recommend the HydroBlu Go Flow gravity kit. It uses the same Versa inline filter, but instead of the soft canteens that come with the base kit, the Go Flow comes with a nice 10 L gravity bag with carry strap, hanging hooks, and a quick-disconnect hose with on/off clamp. This makes it easy to filter large amounts of water without any manual effort. We were originally concerned about the large 10 liter bag, but the whole kit only weighs 10.8 oz and it seems to fold and store nicely enough for a bug out bag. The closest competitor, the Sawyer Gravity System, is essentially the same price but comes with the less-awesome Mini filter and a significantly-inferior bag that’s 60% smaller. There are more popular competitors, like the Platypus GravityWorks, but we can’t justify the extra $80-$120.

Honorable mentions

Absolute best: MSR Guardian pump
Everyday carry: HydroBlu Sidekick pen
Cheapest virus protection: Survivor Filter Straw
Cheapest virus pump: Survivor Filter PRO
Best bottle: LifeStraw Go
Virus bottles: Sagan Journey and LifeSaver Legacy
One kit that does everything: Renovo MUV

Preppers should use a mix of water filters

You shouldn’t buy one thing and be done. Even a minimalist go-bag should have a filter and a purifier, so you have two ways of creating drinkable water. Not just because of backups and the “two is one, one is none” philosophy — a mix of types means you’ll have all of your bases covered and can adapt to the emergency.

Three example mixes (limited to filters) of what you might find in someone’s emergency bag:

Basic: HydroBlu Versa kit + LifeStraw Go bottle = $60
Mid range: HydroBlu Versa Go Flow gravity kit + Sagan Journey bottle + Survivor Straw kit = $130
Upgrade: MSR Guardian pump + HydroBlu Go Flow gravity kit + LifeSaver Legacy bottle = $480

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Why you should trust us

We’ve spent over 48 hours researching and reviewing over 70 products, narrowing it down to the top 5-10 in each category before deeper testing. I’ve been prepping for 14 years, teaching others for 11 years, and have used most of the name-brand filters on this list (and a few of the knockoffs).

How water purifiers fit into emergency preparedness

Following the beginner prepping checklist, there are three main scenarios you plan for:

  • Staying home (bugging in or sheltering in place)
  • Being able to leave your home at a moment’s notice (bug out bags)
  • Being able to get home or get to safety if emergency strikes when you’re away (get home bags and everyday carry)

Even if you’re planning on staying home, one of the core sane prepper rules is that you can’t predict what will happen.

So you should be prepared to survive in case you have to leave or never make it home to begin with, making your home Brita filter worthless. You simply cannot depend on being able to buy water at the last minute, use your bathtub, or get free handouts from FEMA quickly enough to matter.

Combine with:

Best emergency water storage containers for your home
Best emergency water storage containers review

Portable filters compliment the potable water you should already have stored at home! Read more

You should have small water containers for short term emergencies filled and stored in your home that cover at least the first two weeks.

There are better water filter systems that make sense for a prepared home or large groups in fixed positions (like the Berkey filters). But those home filters aren’t practical for portable use and should only be taken on after covering these basics.

Redundancy is built into these models. Which also makes it easy for beginners or those on a budget to baby-step their way in. For example, your bug out bag is always packed and ready at home, so even if you do end up staying home during an emergency, you’ll have these portable filters on hand to compliment whatever larger water gear you have on hand.

Water is very heavy at 8.3 pounds per gallon. People need an average of one gallon per day — if not more when on foot. So the idea you’ll carry the water you need for days is a non-starter.

But we do recommend you keep 16-24 oz of potable water stored in your emergency bags at all times.

Water filters for bug out bags
Rigid bottles are a great way to keep potable water stored in your bug out bag — just detach the internal filter until you need it so it’s not sitting in water.

Water is so important, you don’t want to be worrying about finding a water source and filtering it in the minutes and hours after SHTF. This probably means having a rigid water bottle in your pack, which may or may not affect which filters you buy.

Screws on to most filters:

Evernew 2L Water Pouch

Well-reviewed but affordable water pouch from Japan. Standard 28 mm threading works with most attachable water filters. More popular bag brands like Platypus sometimes don't attach well.
Even if you don’t buy a filtered bottle below, you still need to have some kind of vessel in your bags, so be mindful about the gear you have or need to carry water and/or cook with it.

Think about cross contamination and how you’ll handle vessels that hold dirty water. Once a vessel holds bad water, you’ll ideally not put clean water in it until you’ve washed it out with soap. Some products below even give you separate “clean” and “dirty” bags.

Common risks in untreated water

Some people think “I’ve drank from streams before and never gotten sick, so I don’t need this.” There was even a (debunked) article that went viral arguing against the need for filters.

Don’t buy it. This is an important prep to have.

There are three main categories of water risks: sediments, biological organisms, and toxins. More specifically:

  • Sediment: Solid stuff like dirt, sand, silt, debris, plant and animal matter.
  • Algae: Green/blue/brown slime that grows in still water. The CDC reports harmful algae blooms are increasing due to climate change and industrial waste.
  • Bacteria: Namely from human and animal fecal waste, like E. coli, salmonella, cholera, shigella, and coliform.
  • Protozoa: Larger, more advanced single-cell organisms than bacteria that feed on organic matter, like giardia, cryptosporidium, and cyclospora.
  • Cysts: These are just dormant forms of bacteria/protozoa waiting to ‘turn on’ once inside your body, but you sometimes see them listed separately in product marketing materials.
  • Viruses: Hepatitis A, SARS, polio, and HFMD (hand, foot, and mouth disease) caused by viruses like norovirus and rotavirus.
  • Chemicals, heavy metals, & society’s waste: Countless contaminants like oil, pesticides, cleaning agents, acid rain, industrial runoff, paint, or heavy metals like lead and mercury.
Personal water purifiers giardia risk
Giardia infection in a small intestine (CDC)

The two most common dangers in developed countries like the US and Canada are giardia and cryptosporidium, two unpleasant single-celled protozoan parasites that come from animal feces and can cause severe intestinal problems. They usually have more common non-scientific names like “beaver fever.” Cryptosporidium in particular has a hard outer shell, making it difficult to kill.

Cryptosporidium emergency water threat
Cryptosporidium is hard to kill with chlorination because of its thick outer shell (CDC)

Viruses are generally not a threat in modernized countries with temperate climates, like the US or Canada. Water viruses are much more common in developing countries or areas with extreme climates, like Mexico or India.

Running water is generally safer than still water because nature acts like a filter/cleaner as water moves through it.

Emergency water sources
Running water (left) is usually safer than still water (right) — but it depends on what’s upstream

Non-living toxins are generally more of a threat the closer you are to dense cities and industrial or mining areas. We don’t ever assume water is 100% safe, but water in a remote mountain stream is likely safe from heavy metals and chemicals.

There are no portable survival filters that handle salt water and most won’t handle water-soluble chemicals (like fluoride) or industrial metals.

Water sources in emergencies

It’s important to be adaptable and not pigeonholed into overly-specific scenarios — easily one of the most common prepping mistakes we see everyday, including when buying water products.

Urban water source in disaster
Don’t just think about rivers and lakes — this could be your water source, too

Don’t get tricked by product marketing: Most of you are more likely to be drinking from a dirty urban puddle than a clean mountain creek.

Unfortunately, the sources of water you’d naturally turn to in an emergency are becoming more contaminated every year because of human activity.

Drinking water quality
Humans are absolutely destroying our water sources with plastics, trash, chemicals, metals, etc.

For example, even though 68 million pounds per year of the top 10 toxic industrial chemicals are improperly disposed of (polluting drinking water across America), after a successful lobbying effort by the chemical industry in 2018 the US EPA decided to stop considering the effect of toxins in water when evaluating risk.

During most emergencies, water sources and quality will be the same as normal.

But larger emergencies can quickly contaminate the water, such as hurricanes, flooding, grid/infrastructure failure, industrial accidents, biological contamination, and major SHTF scenarios.

If a storm floods your city, all of the surrounding water is likely tainted with industrial runoff, auto chemicals, and sewage.

Water contamination during hurricane flooding
Houston, Texas after 2017’s Hurricane Harvey (Getty Images/Marcus Yam)

After Hurricane Harvey hit Houston in 2017, the water was so contaminated that people were getting sick just by walking through it. Medical tests showed the water had up to 5,700 times more bacteria than EPA standards.

Industrial disaster chemicals in water
Plants like these were flooded during Hurricane Harvey, contaminating the entire region (Reuters/Nick Oxford)

Only 3% of sewage treatment plants in the Houston area were affected, but that was enough to massively contaminate the whole region — let alone all of the flooded dry cleaners, industrial plants, auto body shops, and so on that released “millions of pounds of pollutants”.

The risks are meaningful. A bout of gastroenteritis or Legionnaires disease will really make your bad days even worse. An emergency is not the time to be broken down from fatigue, diarrhea, and vomiting.

Best personal water treatment method for prepping

Each method has pros and cons — and no single method will make water 100% safe — but in the end we recommend filters for your basic prep supplies.

Types of portable water filters for surviving
Not to scale — the filter shown is 10x smaller and lighter than a distiller

There are multiple ways to clean water in the field:

  • Filter out the particulates large enough to be caught in a fine screen.
  • Purify with chemicals like chlorine (aka chlorination), iodine, or ozone to kill or deactivate bad stuff in the water. Just like a swimming pool.
  • Use UV light to kill living organisms (similar to how medical equipment is sterilized).
  • Boil water to kill living things.
  • Distill water by boiling it and catching the evaporating steam, recollecting it into liquid water. This leaves anything that wasn’t pure H2O behind.

When looking at the kinds of products relevant to personal emergencies, it usually comes down to filters versus purifiers. The best answer is to have both. But if you only have one, a filter is usually the better choice.

Review: Best portable water purifiers

Boiling takes time, fuel, and equipment. It’s a fine method, but it doesn’t make sense as a primary water plan in this context. Think of boiling as a backup or bonus.

While we do recommend having some purification chemicals on hand as a backup, we don’t recommend them as your primary plan.

For example, imagine you have filters in your bag that don’t protect against viruses. But the water around you seems sketchy or you know there’s an outbreak. You would filter the water to remove particulates, then boil it to kill anything left over.

Purifying chemicals seem attractive because they are relatively cheap, small, and lightweight. So they’re easy to buy and throw in a bug out bag pocket.

Besides wanting to avoid putting unnecessary chemicals in your body, chemical treatments take a long time — a normal-sized water bottle can take up to an hour or two to neutralize the hard-to-kill threats like cryptosporidium. Not only do they expire after a few years, but one water filter might clean up to 100,000 liters whereas a normal package of purification tablets might only clean 200 liters.

They’re both technically safe to drink — but wouldn’t you rather drink the clear one?

Chemicals, UV, and boiling will kill living contaminants but they don’t remove particulates and some chemicals. So you might end up drinking water that looks and tastes horrible even though it technically doesn’t have any living threats.

How portable water filters work

Filters use physical mesh screens to block particles. How effective the filter is depends on how small the pore holes are, which determines what it blocks versus what it lets through.

Common sizes:

  • Human hair: 50 microns wide
  • Algae: 5-20 microns
  • Protozoa: 1-50 microns
  • Coal dust: 1-50 microns
  • Asbestos: 0.7-90 microns
  • Bacteria: 0.2-1.0 micron
  • Radioactive fallout: 0.1-10 microns
  • Virus: 0.004-0.3 micron
  • Lead: 0.001-0.7 micron

Note: Some products play marketing games by saying they have a “nominal” size of X microns. This means it can block down to that size, but not always — so look for “absolute” ratings instead. The CDC found that some “nominal 1 micron filters” still let through up to 30% of 1 micron threats.

How survival water filters work
Small pores, like in these hollow fiber bundles, block organisms but not water (Sawyer)

A virus can be 100 times smaller than bacteria, which is why any decent filter can screen out protozoa and bacteria, but only the tightest ones can filter viruses and other super-fine particles.

SHTF water filter lifestraw review
Carbon stages remove bad odors/tastes and some chemicals, like this replaceable carbon filter tip on a HydroBlu Sidekick

Some products mix technology, combining small filter pores with a kind of ionized coating around the mesh that attracts bad stuff as they float through. This is why some filters that are technically only 0.2 micron in size can still filter out 0.01 micron viruses.

Some filters also use activated carbon (e.g. activated charcoal) to attract and trap the smaller stuff that otherwise would slip through a mesh screen — similar to how activated carbon traps gases in prepper gas masks. Carbon will not only make the water taste and smell better, but it can remove some of the chemicals you’d rather not drink.

Fluoride, salt, and other elements are water soluble, which means they dissolve into the water and are no longer separate particulates that can be screened with a filter.

Types of survival water filters

The difference comes down to how the water is forced through a filter. Water is either sucked through via your mouth, pulled through via gravity, or pushed through via a pump or squeezing motion.

  • Straw: The simplest filters that move water through via suction from your mouth as you drink.
  • Bottle: Essentially straws that are mounted inside of a bottle, so they filter as you drink.
  • Inline: Versatile filters that have simple input and output attachment points, so you can use it as a straw directly in the water, screwed onto a bottle top, with a hydration bladder, or with a gravity bag.
  • Gravity: Uses gravity to pull water through filter, typically with a bag of dirty water elevated above an inline filter with hose connections.
  • Pump: Your hand movement forces water through.

One of our frustrations with this market is that most products are designed for a specific hiking, camping, or international travel need — not emergency preparedness. Which creates unfortunate tradeoffs and products that are never quite perfect.

Versatility examples: Attached to standard bottle (left), inline with gravity/bladder hoses (right)

But newer filters (especially the inline models) are becoming more versatile, so you can use the filter in almost any possible configuration or scenario — something very important in prepping so that you can reduce weight and cost while increasing your ability to handle unpredictable scenarios.

Top brands
  • Aquamira: Known for their chemical purification methods, they also created some of the first versatile inline filters.
  • HydroBlu: A relatively new Utah-based player to the market that surprised us with some quality product offerings.
  • Katadyn: Based in Switzerland, this venerable company is known for their tough ceramic pump filters that last a long time.
  • LifeStraw: They blew up and owned the survival straw category, becoming the name brand most laypeople have heard of. But their products are limited and often not the best choice.
  • MSR: Great tech with unique products, but they tend to stay within their own product ecosystem. For example, their pump filters directly attach to their branded water bladders, but don’t come with hoses to easily pump into other third party products.
  • Platypus: A great company with solid products (like water bladder bags), but they don’t seem to make their water filtration stuff in house.
  • Renovo: A new company, their whole thing is a modular, versatile product family. They have three filters (MUV 1/2/3) that connect together, so you can use any combo you want based on the water quality. Those filters can attach to a mouthpiece to make it a straw, inside a bottle, or to a pump housing.
  • Sagan: A relatively new brand in the space from the same California-based folks as Kelly Kettle, and they seem to be doing it right.
  • Sawyer: When we poll preppers, the Sawyer is by far the most-often-recommended brand. We don’t always think they’re the best, but it’s a tried-and-true company with a reputation for filters that last a very long time.
  • Seychelle. Well known in the water purification industry, but their personal products relevant for prepping seem to have fallen behind the curve.

There are brands you often see popping up around sites like Amazon that are actually white-labelled brands that take other people’s products (typically from unknown Chinese manufacturers like Diercon) and slap their name on top. An easy way to tell is if you can’t find a good website for the company.

We try to avoid these products. Common examples:

  • Aquaway
  • Etekcity
  • JBW
  • Life Defender
  • Nature’s Hangout
  • Outdoors 365
  • Survival Hax

How we review the best backpacking water filters

A good hiking or camping product might not be right for emergency preparedness. Context matters.

One example: The risk of contracting a virus from water in America is almost zero in normal life. So a recreational hiker measuring every ounce of carried weight doesn’t need to worry about having a filter that stops viruses. It would make sense for hikers to buy a cheaper filter that lasts longer and has a better flow rate (because of the larger filter pores).

Even if they did get sick, they’d have access to medical care. But both the risk and consequences are greater in some of the worst emergencies, so we consider viral protection more heavily.

We focus on product qualities that make sense for being away from home during a wide range of emergencies, such as:

  • What kind of water and threats will it clean
  • How portable is it
  • Durability and shelf life
  • Ease of use without instructions (the “10 year old child” test)
  • Does it require batteries
  • How much water can it clean without replacements or complicated maintenance
  • How fast does it work

One of the trickiest parts is thinking about how you use various filters. Does it need a bag? Special hoses? Can you only use it in one situation? Will it work when you’re on foot in a suburb? In a desert?

For example, the most popular survival water filters (like the LifeStraw) have serious disadvantages because they only work when you are physically inches away from a water source. You have to bend down and put the straw into the water, sucking in with your mouth.

LifeStraw competition alternatives
Straw models (like this Survivor Filter Straw) require you to get very close to a water source

We greatly prefer products that give us the option to put clean water into whatever vessel we want, for as much quantity as we want.

We generally don’t like “modular” products, like the Renovo MUV, because they typically have more moving pieces, higher risks of failure, can be confusing in the field, and require you to go all-in on their systems.

Best survival straws

  • Avoid straw models. It’s very common that someone new to prepping buys a LifeStraw or something similar as one of their first purchases because they saw a blogspam review promoting it. But there are very few scenarios where we’d rather have a straw instead of the other types.
  • Exceptions: They can be great for everyday carry uses. Or if you really want to have a straw, think of it as a nice-to-have bonus.
  • The difference between a straw model and an inline model is that straws do not have the easy ability to attach standard hoses to the input and output ends, requiring you to dunk the input end in the water and/or use your mouth to bring water through.
  • One of the main disadvantages is that you can’t filter water and then store it in a vessel. It only filters in the moment as you suck water through and into your mouth. Imagine if you wanted to cook or store it for later: Are you going to spit the water back into a pot or bag?
  • Another major disadvantage is you have to get your face a few inches away from the water source. Sounds good in theory, but is more difficult in practice.
  • Can be hard to suck the water through, especially as the filters get clogged up over time and flow rate drops.
  • Pros: cheapest, smallest, lightest, simplest.
Our Picks
Survivor Filter Straw
Best full-size straw:

Survivor Filter Straw

Virus/bacteria/protozoa protection. 28 mm threading on the input end so it attaches to standard water bottles. Difficult to suck water through, easier when attached to a water bag. 0.05 micron filter lasts 1,000 liters (260 gal). 3.5 oz heavy, 7.1" long.
HydroBlu Sidekick Straw
Best EDC straw:

HydroBlu Sidekick Straw

Bacteria/protozoa protection. Tiny 1.0 oz heavy and 6" long pen shape that fits in your purse or pocket for everyday carry. Does not have threaded input end like the full-size straws. 0.1 micron filter lasts 380 liters (100 gal) with replaceable carbon pre-filter.
If you really want to buy a straw model, we like the $30 Survivor Filter Straw for a full-sized option and the $18 HydroBlu Sidekick for a tiny option that works great for everyday carry. Both filters will screen out the common threats like giardia and cryptosporidium, and the Survivor Filter handles most (but not all) viruses.

The Sidekick is great for throwing in a purse, daily bag, or glove compartment with a tiny pen-like form factor and 1.0 oz weight. Comes with an extra carbon pre-filter to keep water tasting fresh, but the overall straw is not easy to clean, not meant for long-term survival use, and has no 28 mm threading or attachment points.

LifeStraw alternative comparison
28 mm threading means you can attach the Survivor Filter straw to a soft canteen — but not the LifeStraw, in blue. Also note the input hose nipple on the Survivor.

Survivor Filter is technically a white-labeled Chinese product (it’s the exact same model as the old Renovo Trio straw). But this brand has been around long enough to establish itself with a responsive US presence and lifetime warranty, and we’ve personally used this straw as a backup for years. We chose it over the better-known LifeStraw because it has a US-lab-tested 0.05 micron filter (LifeStraw’s is 0.2 micron) and a 28 mm thread on the input end so you can screw it directly onto most normal plastic bottles (the LifeStraw can’t). It has a carbon filter and replaceable parts. It’s very difficult to suck through without using the bottle attachments, but good enough when attached to a soft/squeezable canteens — the Survivor Filter Squeeze Kit is $10 more but comes with two 33 oz bags.

The competition

Aquamira Frontier Straw. $12. 110 L (30 gal). 1.0 oz weight. The Frontier straw has been around for a while, but it doesn’t even cover the basic bacteria and protozoa protection levels, instead only covering “protozoan cysts” (which are the largest types of threats). Pass.

Aquaway Pen. $15. 0.1 micron filter for 1,000 L (260 gal). 1 oz weight, 5.4” long. Carbon filter. Comes with pre-filter replacements. No website, likely Chinese or white-labeled. Pass.

Alexapure Survival Spring. $18. 0.2 microns filter for 1,135 L (300 gal). 1.6 oz, 8.8”. Includes a carbon filter. 28mm thread. Sometimes branded as a My Patriot Supply filter. Endorsed by survivalist Les Stroud. Carry lanyard. No backwashing, dispose of after 300 gallons.

Etekcity Straw. $15. 0.1 micron filter for 1,500 L (395 gal). 2.1 oz. 1 year life once used. Can be backflushed. 28mm thread. Carbon filter. This is the white-label version of the Chinese Diercon Straw. Dislike that the pre-filter attachment requires a separate piece of plastic tubing. Comes with a poorly-reviewed soft canteen and pre-filter replacements. Decent protective cap. Lab tested. Likely a white-labeled version from the Chinese manufacturer Diercon.

Glacial Stream Straw. $12. ? micron. 755 L (200 gal). 0.5 oz, 8”. Tiny, like a pencil. Carbon filter. Not cleanable. Unclear product info. Pass.

Life Defender Straw. $20. 0.01 micron. 1,500 L (395 gal). 2 oz. 28mm thread. Can attach tube to inlet. Carry lanyard. Carbon filter. 5 yr shelf life. The protective cap seems weak. Conflicting info from manufacturer regarding filter size and viral protection.

LifeStraw Personal Filter. $17. 0.2 micron filter for 4,000 L (1,040 gal). 1.6 oz, 7.9”. No 28mm threads. Carry lanyard. Relatively large filter pore size for this class, which lets more threats through but is easier to suck. No carbon filter. Independently tested. Popular brand/product with over 88,000 Amazon reviews, but we think it’s overhyped for preppers.

Sagan XStream Straw. $60. 2.0 micron filter for 945 L (250 gal). 6.2 oz, 7”. Virus protection (uses the special mesh tech with larger pores) and lab tested. This is a unique kit that we weren’t sure how to categorize, but Sagan calls it a straw, so here it is. It can be a straw in that you dip a long hose into your source and draw water through the other end with your mouth. But it also has a hand pump bulb (similar to the MSR AutoFlow), so you could squeeze instead of suck, which also makes it usable as a shower and equipment cleaner. Might be interesting for your kit, but we’d think more highly of it if the filter life was better.

Seychelle Radiological Straw. $30. Unknown filter for 95 L (25 gal). Only filters 25 gallons of water because it’s a very beefy filter that covers radiological threats. Only consider this if you’re specifically thinking about nuclear preps. NSF 42 and 53 certified.

Best filtered water bottles

  • We recommend keeping drinkable water stored in your BOB/GHB anyway — using a filtered bottle can be a good way to hit two birds with one stone, even if you keep the filter part detached during storage so it’s not sitting in water.
  • We tend to dislike soft/collapsible vessels with internal filters. They can be great for lightweight hiking, but are not durable enough for emergency preparedness. Many products have consistent complaints of leaks in the vessel. If you’re going to go that route, you may as well get normal unfiltered soft pouches with 28 mm threads (like a Platypus bag) to use with your other, more versatile water filters.
  • Bottle filters generally have a shorter life than other product classes, but are typically replaceable for $10-30. Some are backwashable.
  • Better filters can be harder to suck water through because of the smaller pore sizes. Some bottles are soft or semi-squeezable so you can help push water through, while a few newer models (like the Lifesaver bottles) use extra pump/press mechanisms to assist.
  • Don’t get tricked into buying a “filtered” water bottle that is more about turning tap water into “better” water with pseudoscience marketing for “wellness”, “ionization”, pH levels, fluoride, etc.
Our Pick
LifeStraw Go Bottle
Best for most people:

LifeStraw Go Bottle

Bacteria/protozoa protection. Rigid 22 oz bottle. 0.2 micron filter lasts 4,000 liters (1,040 gal). 5.9 oz heavy. Replaceable carbon filter lasts 100 L.
If you’re not worried about virus protection, we recommend the $40 LifeStraw Go with two-stage filter for most people. It’s a quality 22 oz bottle with a 0.2 micron filter that lasts for 4,000 liters and a replaceable $10 carbon filter that lasts for 100 liters. Weighs 5.9 oz. If you’d rather DIY with your preferred water bottle, the $32 LifeStraw Universal is a cap and filter kit that drops into most standard bottle necks.

Virus Picks
Sagan Journey Bottle
Affordable virus protection:

Sagan Journey Bottle

Virus/bacteria/protozoa protection and some metals/chemicals. Rigid 24 oz bottle with mechanical flip-cap, finger loop, rubber grips. 7.4 oz weight. 2.0 micron filter lasts 945 liters (250 gal).
Aquamira Frontier Flow Bottle Red
Versatile virus protection:

Aquamira Frontier Flow Bottle Red

Virus/bacteria/protozoa protection. 25 oz semi-soft bottle. Versatile because you can swap between basic Green and virus-rated Red filters. Green lasts 378 liters (100 gal), Red lasts 454 liters (120 gal). 7.2 oz weight.
If you do want virus protection, we like the $55 Sagan Journey and $70 Aquamira Frontier Flow. The Journey is a quality 24 oz bottle weighing 7.4 oz. The filter seems loose at 2.0 microns, but Sagan uses the special tech that charges the mesh material, attracting and trapping smaller particles that would otherwise get through. Lab tested with clear info on organisms, and it even removes some heavy metals. We like most parts of the bottle design, such as the mouthpiece, mechanically-retained cap, finger hook, fill lines, and form factor. We dislike how the filter connects to the mouthpiece with a plastic tube, which we fear could degrade over time, and wish the filter sat closer to the top for when the bolted is tilted during drinking. Lasts 945 liters.

The 25 oz Aquamira Frontier Flow semi-soft bottle is nice because you can change between two different filters: The Series II Green filter covers the basics (bacteria and protozoa) while the Red filter adds virus protection. You buy the bottle in either Green ($30) or Red ($70), then you can buy a mix of extra filters, using the Greens for normal use with a Red or two on hand for when things are bad. Another great feature: the removable internal filter has hose attachment nipples on both ends, giving you the versatility of an inline filter. We dislike that the Frontier Flow uses a bite valve, and the plastic cap could be better designed/built. Lasts 378 liters.

Upgrade Picks
LifeSaver Liberty Bottle
Virus protection with pump assist:

LifeSaver Liberty Bottle

Virus/bacteria/protozoa protection. Unique 13.5 oz rigid bottle with built-in pump to pressurize water through the filter, making it easier to draw. 0.015 micron filter lasts 2,000 liters (528 gal). 15 oz heavy.
Sawyer Select S3 Bottle
Maximum bottle protection:

Sawyer Select S3 Bottle

Virus/bacteria/protozoa protection/metals/chemicals (S3). Unique 20 oz soft bottle that uses foam to neutralize threats. 0.1 micron filter lasts 400 uses.
There are two upgrade bottles worth mentioning: the $108 LifeSaver Liberty and $85 Sawyer Select S3, both of which offer virus protection without destroying your cheeks through with hard-to-draw-from filters. The LifeSaver’s super-fine 0.015 micron filter would be too hard to suck through on your own, so there’s a pump built into the base that adds some weight (15 oz total) and reduces overall water capacity (only a 13.5 oz bottle) in order to pressurize the system. Main filter lasts 2,000 liters (528 gal) with a replaceable 100 liter carbon filter. Comes with input and output hoses, so you could also think of this as a pump with a built-in bottle.

The Sawyer Select S3 uses Sawyer’s famous 0.1 micron filtration system combined with an internal foam that treats viruses, heavy metals, and other industrial toxins for 400 uses. It’s a unique approach where you fill the bottle with water and then squeeze/swish it around for 10-15 seconds, activating the foam cleanser. But some reviewers note a foamy aftertaste or even visibly-noticeable residue in the water. 20 oz bottles weighing 10 oz.

The competition

Berkey Sport. $45. 22 oz bottle. 378 L (100 gal) filter. 4 oz weight. Squeeze bottle. Berkey is a well-known water company, but this product is a miss and perhaps white-labeled from a cheaper manufacturer. No clear filter info with vague tech claims. We dislike the mouthpiece tube, as it seems flimsy and there are reports of mold growth and leaks. We also dislike the way the filter hangs inside the bottle.

Brita Bottle with Filter. $9. 20 oz bottle. 150 L (40 gal). Popular brand, but this is not a survival filter, similar to how their well-known kitchen filters just make tap water “better”. Pass.

Grayl Ultralight Filter Bottle. $70. 16 oz bottle. 150 L (40 gal) filter. 2.0 L/min. 10.9 oz. Virus and metal protection. Popular and well-reviewed, but we think it’s only desirable for stylish everyday carry. Carbon filter. Smaller bottle, partly due to a design that uses a unique “french press” motion instead of filtering as you suck water out. Innovative, but we have concerns about this design in an emergency context (including the very small lifespan) and reports of leaks and cross-contamination increase our suspicion.

HydroBlu Clear Flow. $22. 24 oz bottle. 0.1 micron filter for 1,500 L (395 gal). 7.8 oz weight. Carbon filter. There were significant reports of leaks and failures in 2017, but HydroBlu tells us in 2018 that they’ve fixed the issue. We’re not a fan of the physical bottle design, including how the filter attaches to the inside of the cap.

Katadyn BeFree Collapsible Bottle. $40. 20 oz soft bottle. 0.1 micron filter for 1,000 liters (260 gal). 2 oz weight. Katadyn is a solid company, but this tiny “crushable” bottle is built for ultralight hiking in normal life, not emergency preparedness, and we’ve seen reports of bag failure and durability issues. Although it could be a good option for compact EDC. Recently selected as an Editor’s Choice by Outdoor Magazine.

LifeSaver 4000UF Ultra Bottle. $158. 25 oz bottle. 0.015 micron filter for 4,000* L (1,056 gal). 22 oz weight. Most expensive and heaviest bottle on our list because it has a pump built into the base, which reduces the pressure you need to create from sucking. Good filter that includes virus protection. Carbon filter, but only lasts 500 L, replaceable for $10. Lab tested. Seems well built but there are reports of pump failures / leaks, and we dislike that you have to scoop the mouthpiece end into contaminated water.

Miniwell L620 Soft Bottle. $21. 23 oz bottle. 0.1 micron filter for 1,000 L (260 gal). 2.9 oz weight. Chinese, questionable service / support and inconsistent product info. We don’t like the soft bottle design in these products because it doesn’t protect the filter while in your bag. Carbon filter. Lab tested.

OKO H2O Level-2 650ml Bottle. $25. 22 oz bottle. 2.0 micron filter for 378 L (100 gal). 4.9 oz weight. Softer bottle, which we dislike. Filter is not backflushable and uses a NASA-derived tech with larger pore sizes and charged mesh materials. Higher than normal reports of leaks / quality issues.

Platypus Meta 1.0L. $37. 25* oz bottle. 0.2 micron filter for 1,000 L (260 gal). 6.9 oz weight. Unique bottle design withs pros and cons. We not fans of how the split design reduces the amount of water you can carry and/or makes it larger than it needs to be — reducing the stated 1.0 L capacity to about .75 L (25 oz). Pro: The top half is rigid, protecting the filter assembly, while the bottom half is squeezable, which helps with pushing water through the filter. Higher than normal negative reviews and reports of product quality problems. Easy to clean filter in the field.

Purewell Bottle. $25. 22 oz bottle. 0.01 micron filter for 1,500 L (395 gal). ? weight. Looks white-labeled, identical to the Life Defender bottle, with no US company web presence. Carbon filter. Comes with small compass integrated in cap and a cheap paracord bracelet and flint.

Renovo MUV Nomad. $27. 24 oz bottle. ? micron* filter 340 L (90 gal). 8.5 oz weight. Virus protection*. Lab tested. We like the mouthpiece flip cap design. Renovo uses modular filters, MUV 1-2-3. MUV1 is a carbon filter and MUV2 is a 0.1 micron filter (good, but no viral protection). MUV3 uses the same large-pore charged filter NASA tech as the OKO bottle, which probably works fine for normal use, but we’re uncomfortable with for long-term emergency uses. You could probably put the MUV2 filter in the Nomad bottle, but the bottle comes with the MUV3 filter — which does filter viruses but only has a 340 L life. It doesn’t look like you can stack more than one of the MUV modular filters together inside the bottle.

Sawyer Personal Filtration Bottle. $44. 34 oz bottle. 0.1 micron filter for 378,000 L (100,000 gal). 5.5 oz weight. The 0.1 micron filter is “absolute”, so it’s still a great filter that lasts a tremendously long time. Comes with backwash syringe. Filter assembly can be removed and used inline with bladders/gravity bags. Easier to drink through than other filtered bottles. But we think the bottle/cap design and durability should be better. 63 mm bottle cap assembly (including filter) can fit on Nalgene-style bottle. Sawyer is a top name in prepper water filters.

Seychelle Flip Top Bottle “Advanced”. $30. 28 oz bottle. Unusual filter for 378 L (100 gal). 4.8 oz weight. Multiple models. The Advanced model removes viruses and has some extra iodinated resin tech to remove metals, fluoride, and radiation (unusual for bottle filters). Seychelle is a reputable company, but this squeezable bottle has higher than normal reports of leaking. Doesn’t work well when less than half full.

SurviMate Water Filter Bottle. $27. Another white-labeled copy of the same Purewell, Life Defender, etc bottles above. We don’t believe the micron rating. Pass.

WaterBasics Filtered Bottle. $30. This is the same Aquamira bottle above, and made/sold by Aquamira, but sometimes listed as a separate brand.

Woder 24-Sur Bottle. $24. This is a white-label version of the Berkey bottle above. Pass.

Best pumps

  • Pumps are great because you do the work with your arms instead of your mouth.
  • They usually come with input and output hoses. Some include a sanitation bag to keep your output hose clean during storage.
  • Pumps work better than most other types in shallow water sources like puddles.
  • You can create as much clean water as you want… just keep pumping.
  • Many pumps use ceramic for their filters, a naturally porous material that traps particulates. Unlike membrane-based filters that use backflushing to clean out the trapped particles, ceramic filters are scrubbed down by hand with a brush or cloth. It’s easy to do and has some advantages, such as visibly seeing how much life the ceramic has left (instead of guessing on other types) and you don’t need a backflush syringe.
  • Ceramic filters can’t block viruses.
  • Pumps only work when you’re pumping them. You can’t daisy chain them with a bladder, bottle, or gravity bag the way you can with inline models.
Our Pick
Katadyn Hiker Pro Pump
Best pump for most people:

Katadyn Hiker Pro Pump

Bacteria/protozoa protection. Replaceable 0.2 micron glass-fiber/carbon filter lasts 1,135 liters (300 gal). 11 oz heavy, 6" long. Carry pouch. Pro model includes quick-disconnect hoses and better pre-filter.
If you care more about product quality over virus protection, we like the Katadyn Hiker Pro at ~$85. Its 0.2 micron glass-fiber/carbon filter lasts for 1,135 L (300 gal). The 11 oz weight and 6” length is about middle of the road for this class. The main benefit over the base Katadyn Hiker model is the quick-disconnect hose attachments and better pre-filter, which are worthwhile upgrades and reduce possible problems. Filter is easy to clean in the field. Uses the same filter as the base Hiker, but is able to handle more sediment in the water and thus lasts longer. Can buy hydration bladder attachments. Better overall than the direct competitor MSR MiniWorks EX, although the EX does have limited metal/chemical protection.

Virus Pick
Affordable virus pump:

Survivor Filter PRO Pump

Virus/bacteria/protozoa protection. Cheapest virus pump, but uses all-plastic parts. 0.01 micron hollow-fiber/carbon filter lasts 100,000 liters (26,000 gal). 8 oz heavy, 6.5" long. Carry pouch.
If you care more about virus protection but want a sub-$100 pump, check out the $70 Survivor Filter PRO. The tiny 0.01 micron hollow-fiber/carbon filter lasts for 100,000 liters (26,000 gal) and even removes some heavy metals. Weighs 8 oz at 6.5” long. Much lower flow rate compared to other pumps. Reviewers complain of cheap construction quality with mostly plastic parts, which is a big concern for pump-style filters, so don’t expect this to be as much of a durable workhorse as the MSR or Katadyn models. Backwashable. Lab tested in the US, but we’re a little skeptical about some of the filtration and lifespan claims — for example, it’s doubtful the replaceable carbon filter lasts the claimed 2,000 liters.

Upgrade Picks
MSR Guardian Pump
The best portable filter:

MSR Guardian Pump

Virus/bacteria/protozoa protection. Never needs manual cleaning. 0.02 micron hollow-fiber filter lasts for 10,000 liters (2,640 gal). 17.3 oz, 8.25". Carry pouch. Lifetime warranty.
Katadyn Pocket Pump
Extremely durable:

Katadyn Pocket Pump

Bacteria/protozoa protection. Built like a tank with all-metal parts. 0.2 silver-impregnated ceramic filter lasts 50,000 liters (13,000 gal). 20 oz heavy, 10" long. Carry pouch. 20 year warranty.
Originally designed for the US military, the MSR Guardian is one of the best survival filters of any style on the market — with a $390 price to match — and is one of the few pumps that filters out viruses. We even decided to put one in our personal supplies after this review, complimenting the smaller, more portable options in our go bags. The tiny 0.02 micron hollow-fiber filter lasts for 10,000 L (2,640 gal). It’s hefty at 17.3 oz and 8.25” long but not enough to feel unreasonable.

A unique self-cleaning function means you never have to clean or scrub the filter the way you do with other pumps because 10% of the water is used to backflush itself on every stroke. Very high 2.5 L/min flow. Freeze-resistant. No carbon though, so it won’t do much for the taste or chemical protection. The bottom can screw onto a wide-mouth Nalgene bottle so the output water drops right in. We wish it came with an output hose, but you can add one if you’d like or use hoses/attachments from other systems/bladders. We also wish it had stronger materials like the Katadyn Pocket. Limited lifetime warranty.

The Katadyn Pocket is a very popular upgrade that can usually be found for cheaper than the Guardian. The 0.2 micron silver-impregnated ceramic filter lasts for a huge 50,000 L (13,000 gal). The Pocket is even larger than the Guardian at 20 oz and 10”. But some preppers feel it’s the best portable water filter on the market solely because it’s built for extreme use — this Swiss-made product is durable and well built, with solid metal parts instead of the plastic found on most others. Extremely long filter life, enough to keep one person alive for over 15 years. We wish it was easier to dry out for storage / during freezing temps, but it’s a minor complaint. Doesn’t come with a carbon filter, but they sell a carbon add-on piece. 20 year warranty.

The competition

Diercon Survival Filter. 0.01 micron hollow-fiber/carbon filter for 3,000 L (792 gal). 8.7 oz weight, 5.8” long. 600mL/min flow rate. Pump housing seems durable. Chinese, looks like they make many of the white-labeled products sold under middleman brands. Likely difficult to get support, but seems to pass muster with lab testing etc.

General Ecology First Need Elite XLE. $162. 0.4 micron filter for 680 L (180 gal). 16 oz weight, 6.25” long. Too large and cumbersome with not enough filter life for portable emergency use. Self-cleaning pre-filter and gravity assist system included. Can buy adapters for Nalgene/Platypus bottles or standard 28mm water/soda bottles. Unclear filtration info.

Katadyn Combi. $220. 0.2 micron ceramic/carbon filter for 50,000 L (13,000 gal). 21 oz weight, 11” long. At one point in the 2000’s the Combi was the best-selling preparedness filter — and it is a good, beefy filter — but not practical for personal prepping. It’s built for multiple uses, so you can take it out backpacking or attach it to your sink at home or in an RV. The extra cost and size/weight is not worth those features, so we prefer other models.

Katadyn Mini. $100. 0.2 micron ceramic/carbon filter for 7,000 L (1,850 gal). 7 oz weight, 7” long. Katadyn describes the Mini as less effective with backcountry water than the Hiker Pro, so while this is a good model, it loses to the Pro. Almost two-thirds lighter than the venerable Katadyn Pocket, but the portability and long filter life comes with the downside of taking longer than average to pump a liter of water. Silver-impregnated filter. Easy to clean in the field, with a smart built-in measurement tool that tells you when the filter is no longer good enough. The Mini has less pieces than the other Katadyn filters, which we always prefer. The input hose wraps up inside itself to store inside a compartment on the bottom of the filter, reducing the worries about cross contamination during storage.

Katadyn Hiker. $70. 0.2 micron glass-fiber/carbon filter for 750 L (200 gal). 11 oz weight, 6” long. A popular model for hikers, but for ~$20 more go with the Hiker Pro, which comes with better quick release hose attachment. Uses the same filter as the Hiker Pro and accessories as the other Katadyn products.

Katadyn Vario. $87. 0.2 micron glass-fiber/ceramic/carbon filter for 2,000 L (530 gal). 15 oz weight, 7” long. They named it a Vario because it has various filtration settings like “fast mode” and “dirty mode”. Fast mode is for cleaner water. This could make sense for hikers and campers, but in an emergency situation we think it’s counterproductive and prefer other models. Innovative dual-stroke lever pump, which pushes water through on the up and down strokes, resulting in a faster per minute flow rate. Has rechargeable carbon filter, but we dislike the way it’s done.

MSR HyperFlow. $135. 0.2 micron hollow-fiber filter for 1,000 L (265 gal). 7.4 oz weight, 7” long. We applaud MSR’s effort to bring their tech into smaller packages, but there are too many negative reviews about product failures, clogged filters, and complicated instructions for us to be comfortable with it for prepping — especially at $100.

MSR MiniWorks EX. $110. 0.2 micron ceramic/carbon filter for 2,000 L (528 gal). 16 oz weight, 7.5” long. Limited metal and chemical protection via the carbon core. This model effectively replaces the old and popular MSR Sweetwater. Field maintainable without any tools, although there are higher-than-usual reviews about the filter clogging quickly, requiring frequent cleaning, and durability issues around the pump handle/piston. Similar to the Guardian, it’s designed to directly attach to certain bladders and Nalgene-style bottles, or you can attach a hose to the output nipple. Limited lifetime warranty.

Renovo MUV Backcountry. $68. 0.1 micron hollow-fiber/carbon filter for 378,000 L (100,000 gal). 13.5 oz weight. Similar to our criticism of other Renovo MUV products (which are designed to all be modular and swappable in the same product family), we think their hyper-modular design is innovative and potentially nice for normal hiking, but too overcomplicated for prepping. This pump only works when held vertically and has a 1-star rating on Amazon.

Seychelle Pump 2 Pure. $50. 0.2 micron filter info for 378 L (100 gal). 13.6 oz, unknown length. One of the few pumps that filters viruses, and the only that filters radiological contamination. But it only lasts for 100 gallons. Skip this model unless you very specifically care about radiological threats.

Best inline water filters

  • If you’re only going to buy one filter, make it an inline model.
  • The most versatile type — can be used on its own as a straw directly into a water source, screwed onto the mouth of a normal water bottle, attached to the hose of a hydration bladder, or even attached to the output hose of a larger vessel/bucket of water.
  • The best models are surprisingly small and light, because they don’t have any pumps or other functions/attachments.
  • Wide ranges of lifespan. Some models only last for 180 liters and some last up 378,000 liters. Don’t get caught up in the super-huge numbers though.
  • All else being equal, a product that claims 300,000 liters isn’t inherently better than one claiming 200,000.
  • No inline models filter viruses. Some unknown / Chinese manufacturers claim they do, but we’re skeptical.
Our Pick
HydroBlu Versa Inline Filter Kit
Best single product for most people:

HydroBlu Versa Inline Filter Kit

Bacteria/protozoa protection. The kit includes two soft attachable water bags, a hose, hose clamp, and bucket adapter. 0.1 micron filter. Lasts 378,00 liters (100,000 gal). 1.5 oz heavy, 5.5" long.
Platypus GravityWorks alternative competitors
Good inlines easily turn into a DIY gravity setup

Our top inline pick is also our overall recommendation for most people. The HydroBlu Versa ($23 for filter alone, $26 for kit), named so for its versatility, has a lab-tested 0.1 micron filter lasts for 378,000 L (100,000 gal). The tiny 1.5 oz package is slightly larger than the popular direct competitor Sawyer Mini but smaller than the Sawyer Squeeze. Reviewers note the extra size allows for a flow rate that’s noticeably better than the Mini — a frustration that has lead many to abandon their Mini. Backflushable. We appreciate the 28 mm threads on both ends, something almost no other filter offers. The kit, which is only ~$3 more than the Versa filter by itself, includes two 64 oz collapsible bags, a tube, and a bucket adapter for gravity setups — making this a cheap gravity kit, too.

The competition

Aquamira Frontier Pro Ultralight. $30. 0.2 micron filter for 180 L (50 gal). 2.5 oz weight. One of the original versatile filters. Can run it as a straw, attached to a standard 28mm bottle, inline with a hydration bladder, or inline with a gravity bag. Uses Aquamira’s replaceable Series III Green line filters (bacteria/protozoa, no virus protection). Lab tested.

Aquamira Frontier Max. $50. 0.2 micron filter for 454 L (120 gals). 2.5 oz weight. Upgrade version over Aquamira’s Frontier Pro. No 28mm threading, is meant for hoses only. Universal quick disconnect hose nipples. The Pro uses Series III Green filters, while the Max uses Series IV filters in either Green (bacteria/protozoa) or Red (+ virus) versions. Lab tested. Some reviewers note the flow rate is lower than average for this class. Comes with a bite valve attachment to turn it into a straw.

LifeStraw Flex. $35. 0.2 micron filter for 2,000 L (528 gal). 1.7 oz weight, 4.7” long. Comes with a 22 oz collapsible water bottle, but reviewers don’t think the bag is durable enough to depend on (similar to the Katadyn BeFree). 28 mm threads on the input end. Besides normal bacteria/protozoa protection, it filters out some heavy metals like lead — the only LifeStraw model to do so. Replaceable carbon filter that lasts about 100 L. Backwashable.

OKO Survivor. $30. 0.01 micron filter for 100,000 L (26,400 gal). 3.9 oz heavy, 5.25” long. Virus protection with “absolute” 0.01 micron rating tested in US labs. Comes with some hose and a bite valve, plus a bulb-style hand pump you can run inline to squeeze water through with your hand, making it versatile as a shower or equipment cleaner. Seems like a decent kit and filter for the price, but we can’t find much about the product/testing and it’s not available on any common vendors.

Purewell Filter. $13. 0.01 micron filter for 5,000 L (1,320 gal). 2.0 oz weight, 5.4” long. Chinese company with unverifiable filter claims. 28 mm threads on the input end. Filter is not replaceable, but is backwashable. Pass.

Renovo MUV Survivalist. $65. 0.1 micron filter for 378,000 L (100,000 gal). 9.2 oz weight. Virus protection. Part of the Renovo MUV modular system. We don’t think the Renovo products are worth it unless you buy the entire kit so you can get the benefit of all the modular options. Otherwise, each specific type is inferior to competitors, a kind of jack-of-all-trades-master-of-none problem. It’s an interesting concept and we love innovative manufacturers, but in this case it feels too complicated and too easy to misplace the parts. 28 mm thread, mouthpiece adapters, etc.

Sawyer Mini. $20. 0.1 micron filter for 378,000 L (100,000 gal). 2.5 oz weight. The most popular portable water filter for preppers — but we think it’s no longer the clear winner, and if you’re going to buy a Sawyer, many reviewers advise going with the Squeeze + aftermarket attachment parts instead. An easy to use and tiny package with a very long life. We dislike the flow rate compared to its bigger brother the Squeeze (which is 2x faster) or competitors like the HydroBlu Versa, and many other reviewers highlight the same criticism. Because of its tight package, it needs to be backflushed more often than competitors. There are also reports of seals/attachment points breaking, but that could be noticeable simply due to how many people own one. Comes with a 16 oz collapsible bladder and a tube straw. 28 mm threading on input. Backwashable. Lab tested. If you have one or get it anyway, check out the Sawyer Bucket Kit.

Sawyer Squeeze. $30. 0.1 micron filter for 378,000 L (100,000 gal). 3 oz weight. In many ways the Squeeze is similar to it’s smaller brother, the Sawyer Mini, but with a faster flow rate (over 2x better than the Mini) and less frequent need for backflushing. The downside is it’s slightly larger and has fewer out-of-the-box configuration options. The core use-case is the same: Fill the included 32 oz collapsible bladder (or any 28 mm threaded bag) with dirty water, screw on the Squeeze, then squeeze water out into any clean water vessel. It does have aftermarket attachments to place it inline with hydration bladders or gravity bags, but it feels like an afterthought configuration. The complete kit is about $20 more than the base model. Lab tested.

Best gravity kits

  • Produces more water per minute than most other types and requires the least amount of physical effort because gravity does the work instead of your mouth or hand.
  • Gravity kits are usually just a hangable bag and hose with an inline filter attached to the output hose. Some have the filter built inside the bag itself.
  • Gravity bags are very popular and often the highest-rated portable filtration products in outdoor-focused publications or stores like REI.
  • But that popularity is usually in a family camping context, because they filter water for large groups of people without much effort or moving around.
  • We think there is prepping value in having the option to use gravity. It can make daily chores in a fixed position (like your home) much easier. But it’s a nice-to-have on top of a good foundation, not a need-to-have.
  • We don’t like most of the off-the-shelf kits for one big reason or another.
  • A DIY approach is probably better, where you pair an inline filter with any bag and hose. But our top choice gets you 95% of the way there. Assuming you have an inline filter anyway (like the Sawyer Mini), the extra weight/space of adding a gravity water bag and hose in your emergency kits is worth the benefit.
  • Gravity bags are hard to use when water isn’t plentiful or deep, and you need elevated places to set the bag. They work well in wooded areas with lakes and rivers. But you shouldn’t assume that’s where you’ll be in an emergency.
  • The models that use an inline filter on the output hose are easy to backflush. You just flip the filter around and let gravity push out the particulates.
  • We don’t think you need two bags in a gravity kit. You always need a dirty bag. But the value of a special clean bag isn’t really applicable to prepping, except for the value of having a second bag to replace a torn dirty bag. If you need to fill something up, like a bottle or cooking pot, just take it to the dirty bag and let gravity fill your vessel. A separate clean bag doesn’t really improve that process except for saving small amounts of time.
Upgrade Pick
HydroBlu Go Flow Gravity Kit
Best gravity kit:

HydroBlu Go Flow Gravity Kit

Bacteria/protozoa protection. Gravity kit includes the best-in-class Versa inline filter plus 10 liter bag, hose, hope clamp, and storage pouch. 0.1 micron filter. Lasts 378,00 liters (100,000 gal). 10.8 oz weight.
If you want to buy an all-in-one gravity kit and be done with it, we recommend the $45 HydroBlu Go Flow. It comes with their best-in-class Versa inline filter (0.1 micron for 378,000 liters), which we recommend you have on hand anyway even if you don’t care about gravity setups. For $20 more than the filter by itself you get a decently-built large 10 L bag with carry strap and hook clamps, plus a hose and storage pouch. The total kits weighs 10.8 oz. We were originally concerned about the unnecessarily-large 10 liter bag, but it seems to fold and store nicely enough for a bug out bag.

The closest competitor, the Sawyer Gravity System, is almost the exact same price but comes with the Mini filter (which we think is inferior to the Versa) and an inferior bag that’s 60% smaller. The MSR AutoFlow, MSR TrailBase, and Platypus GravityWorks are all popular and well-reviewed options, but we can’t justify the extra $80-120 price without clear benefits for preppers.

The competition

Katadyn Gravity Camp. $65. 6 L bag. 0.2 micron filter for 1,500 L (395 gal). 11 oz weight. The filter in this model is integrated into the bag assembly, rather than simply adding a separate inline filter model to a bag kit — a slight disadvantage, because the inline filters are easier to repurpose, but at this price you could also buy a separate inline filter (like the Sawyer Mini) and still be cheaper than the singular MSR/Platypus kits below. There are reports of this filter clogging too early in its life. We like the sediment trap feature that prevents dirt from getting into the main filter but wish the output hose had a better on/off valve. The best-in-class bag has a transparent stripe so you can see the water level. Quick detach hoses. Can attach output to many hydration bladders. Converts into a shower with aftermarket adapter. Field cleanable.

LifeStraw Mission. $120. 5 L bag. 0.02 micron filter for 18,000 L (4,755 gal). 13 oz weight. Virus protection. 12 L bag option. Field-cleanable pre-filter in the bag. We think it’s a little over complicated to use, with a primer pump that isn’t intuitive for our “10 year old child” test. But it’s a solid filter with a long life.

LifeStraw Family. $70. 12 L bag. 0.02 micron filter for 18,000 L (4,755 gal). 15 oz weight. We’re not really sure why LifeStraw has the Mission and the Family product lines. They’re essentially the same thing, with the Family using a rigid “bag” instead of the collapsible roll-top bag on the Mission. The large rigid container effectively disqualifies this for portable emergency preparedness.

MSR AutoFlow. $120. 4 L bag. 0.2 micron filter for 1,500 L (395 gal). 11.1 oz weight. Basic bag with an inline filter in the output hose. MSR oddly doesn’t specify the filtration ratings for this product, other than the standard “removes protozoa and bacteria”. The filter is the exact same as the other highly-ranked Platypus gravity kit. Reports that the new 2017 version has a cheaper bag material than before, making it lighter but reducing durability. This kit comes with one bag (the Platypus comes with two), which we like because you’ll likely be carrying other vessels anyway, but dislike because it should then be cheaper than the Platypus (but isn’t). Output attaches to many common bottles and bladders. Field cleanable, backflushable.

MSR Trail Base. $160. 2 L bag. 0.2 micron filter for 1,500 L (395 gal). 20 oz. This is a new combo of the MSR TrailShot filter and a version of the MSR DromLite 2L bags — MSR’s attempt to make a gravity bag that’s also useful when moving, because the squeeze-pump filter portion can be used on its own like a normal inline filter or even a direct straw. Slower flow rate than the MSR AutoFlow. Quick disconnect hose attachments. Field cleanable. In the end, we like this kit, but you can get the same or better benefits and optionality for less money and weight.

Platypus GravityWorks. $120. 4 L bag. 0.2 micron filter for 1,500 L (395 gal). 11.5 oz weight. One of the two most-often-recommended gravity kits, alongside the MSR AutoFlow, but it’s better for stationary camping than portable survival. Uses the exact same inline filter as the AutoFlow but comes with two bags (clean and dirty) instead of the MSR’s one. They also offer a single 2 L bag kit for $20 less. We dislike the zip-loc style bag closure, but think these bags are more durable than those in the MSR kit. Field cleanable, backflushable.

Renovo MUV Tote. $49. 0.1 micron filter for 378,000 L (100,000 gal). 10.6 oz weight. Not worth it as a bag kit. If you’re going to buy Renovo, you may as well get their complete modular kit, otherwise you’re taking on the downsides of their products without any of the benefits (modular versatility). Uses the same 10 L bag as the HydroBlu Go Flow with a hose and the standard Renovo MUV2 filter. Comes with mouthpiece to turn the filter into a straw.

Sawyer Gravity System. $40. 3.8 L bag. 0.1 micron filter for 378,000 L (100,000 gal). 8.8 oz weight. Simple combo kit of the popular Sawyer Mini inline filter with a 1 gallon bag and hose. Includes a push/pull on/off valve cap. The Mini is 28mm threaded on each end, so you can take it out of the gravity setup and use it like a normal Mini (e.g. screw it onto a normal water bottle). The bag is notably inferior to other kits, so you could always buy any hanging bag with hose output you’d like and just put a Mini filter inline.

Sawyer Point Zero Two. $110. No bag. 0.02 micron filter for 378,000 L (100,000 gal). 12.8 oz weight*. Virus protection. A unique kit from Sawyer that doesn’t come with a bag — it comes instead with equipment to make your own gravity setup using any bucket. The size and weight are just for the kit. In the end we don’t think this makes sense for portable setups, but could be a great home-based kit. Also comes with a faucet adapter, which makes backflushing this very fine filter easier and more thorough, extending its life.


    • Jonnie PekelnyContributor

      What is the typical use for a filtered water bottle in an emergency situation? Is the idea that you’re scooping up dirty or otherwise untreated water from a water source and just sipping it through the filter in the water bottle? Then don’t you have basically a contaminated water bottle?

      7 |
      • John AdamaStaff Jonnie Pekelny

        Correct, and you’re thinking through it well. You can also have a separate dirty water vessel that you pour into the filtered bottle as a way to keep more of the outside/lip of the filter bottle clean.

        There’s no black and white “right” answer to how to do this, it’s just a matter of thinking through it for your setup, which is why we touch on it in the article.

        5 |
    • Hal Dey

      Is there an activated charcoal filter available to be used with an in-line filter (piggy-back style)?
      Somewhat along the lines of source (bladder, bottle, whatever) – hose – in-line filter (go-flow, Sawyer, whatever) – hose – charcoal filter(for taste, chemicals, etc.) – hose – mouthpiece. (Order not significant)
      Basically I’m looking for particle, biological, taste filtration that’s portable.

      2 |
      • John AdamaStaff Hal Dey

        Many of the models above have a charcoal/carbon filter for taste as part of the overall product. Particularly the straws (whereas the inline filters tend not to). The HydroBlu Sidekick is an example.

        Nothing comes to mind for a stand-alone charcoal filter you can splice in as you described. It’s not a bad idea and should work, but it’s not something we’ve researched.

        6 |
      • squirrel Hal Dey

        Check out the Platypus GravityWorks Carbon Element (good for 300 liters) or the Katadyn Carbon Cartridge (refillable, good for 200 liters or 6 months).

        4 |
    • heatherjasper

      Thanks for the information about the HydroBlu kit. I only heard about their Sidekick, but not the Versa. I have replaced the Sawyer gravity kit and the Mini with the Versa kit in my Amazon shopping list; can’t wait to get it!
      Have you heard about the Oxgord Aqua Marina straw? Do you have any opinions on it?

      5 |
      • John AdamaStaff heatherjasper

        Would love to hear what you think of the Versa once you test it, especially since you used the Sawyer too (it’s essentially a contest between the HB Versa and S Mini). I’m not familiar with the Oxgord, but just checked it out and it smells like a white-labeled me-too product you should avoid.

        7 |
    • Jim Befit

      PLEASE EXPLAIN yourself, there are soo many battery powered UV lights available. If on the run so to speak, it’s quick, could be rechargeable with a solar battery charger which is versatile! And long term important. What is considered living organisms? what about fecal matter- is it living organism’s? are the LED UV’S not powerful enough? Aren’t VIRUSES considered living?? Seems like an efficient way to kill those. Thank you.

      7 |
      • John AdamaStaff Jim Befit

        You don’t see many experienced preppers rely on a UV light because there’s too many breakable parts and points of failure, they aren’t as rugged or versatile as other options, you won’t get the overall volume from a UV the way you would from a Sawyer etc, and the UV doesn’t remove particulates.

        Yes, fecal matter can have living organisms. Whether or not viruses are considered alive is a debate, but its okay in short-hand to refer to viruses as living. https://askabiologist.asu.e…

        7 |
      • Jim Befit John Adama

        ok, not trying to be argumentative, just not yet satisfied. yes, UV doesn’t remove particles, Kinda no brainer, But if you remove particles but not virus’s-( the most difficult and expensive part you said,) but can kill viruses with a $5-$20 UV LED light, why not? Too many pieces? Have you seen how durable LED flashlights ARE? Some are LED/UV Flashlights. if you can’t afford a .001(?) filter, can’t hurt to use one LED-UV after particle filter so you can to kill living organisms?
        Thank you for your last reply, read from you soon.

        5 |
      • John AdamaStaff Jim Befit

        It’s certainly workable to buy a cheaper filter that handles bacteria etc but not viruses, then boil or use a UV pen on the post-filtered water to kill the rest. It’s just not what we and the experts we interview for these stories like to recommend for most people — I have yet to see a UV product that makes me think “yeah, I’d rather carry this in my go bag than the HydroBlu/Sawyer/etc.” There’s almost never a Singular Right Answer in prepping, so do what works for you.

        p.s. keep in mind that viruses are very much an outlier concern in American water supplies.

        6 |
      • Dan Ello John Adama
        [comment deleted]
        5 |
    • Karen Kory

      John, thanks for this incredible article.
      One question, are you not concerned with claims that some of these producers make (like HydroBlu) that are not substantiated by test results (other than some Chinese no-name lab) or certification? Seems like these recommended products look awesome, but since their use could be in a life-threatening situation, it’s a lot to rely on ‘their word’ imho.

      6 |
      • John AdamaStaff Karen Kory

        Thanks Karen, and high five for being skeptical about those kinds of company marketing claims. We always are as well.

        I hope to one day do a proper scientific test, where we try different types of contaminated water with various filters and send the results to a lab for verification. For now, we’ve used a skeptical eye for b.s. (we’ve got a pretty good nose for it), read through lab reports provided to us by manufacturers (can also smell the b.s. reports), interview the managers (shady ones typically won’t get on the phone with press), and cross-checked with any other user reports around the web of giardia etc after use.

        That mix is enough to make us comfortable, and it’s a lot more than most ‘reviews’ you see on the web.

        Frankly, even when something is third-party certified, you still run risks. There’s just no way to remove all possible risk. Just last month we found that a manufacturer with full military certification was actually sending sub-standard product, because their supplier changed the previously-certified materials without letting the company know.

        7 |
      • Karen Kory John Adama

        Ugh… I bet stuff like that does happen,more than we’d like to know — especially with China manufacturing (at least according to my husband’s very frustrating production experiences there). Thanks for the speedy reply and all your great work. Invaluable, and much appreciated.

        4 |
    • Bill Coulam

      This is one of the best articles I’ve ever seen on water filtering and purification. Really well done research and organization. I’m surprised nothing from RapidPure showed up here in your review. A company out of Minnesota. Fantastic capacity, unbeatable flow rate, and 6-log virus-removal to boot. Last time I checked, their site was Did you already know about their stuff and exclude it for some reason? I think they’ve been around since at least 2012.

      7 |
      • John AdamaStaff Bill Coulam

        Thank you. RapidPure wasn’t excluded for a particular reason, so I’ll add to the list for future consideration. Are you affiliated with them?

        6 |
      • Bill Coulam John Adama

        Nope. Just a fellow preparedness aficionado.

        6 |
    • KC

      My problem is a good filtration system for my get home bags.  Because the bags are stored in the car, they are exposed to freezing temperatures in the winter, which renders most of what you reviewed useless as the filters are destroyed if they are frozen.  Perhaps one of these is not susceptible to freezing?  I haven’t gone through every single one, but from what I have found so far they all have that problem.  Right now my thought is coffee filters for large particles and water purification tablets (can those be frozen?).  Any thoughts?

      7 |
      • John AdamaStaff KC

        You’re right that most any filter is at risk of freeze damage — filters by nature use small engineered pores to block the bad stuff, and engineering at that small level can be damaged. But as far as I know, the real freeze risk is from leftover water inside the filter, so if you either have an unused filter* or can let it dry out after use (which is good practice anyway), a dry filter should be okay in your car over winter.

        *unused: You should always use your emergency gear before an emergency, but since many people have multiple of the same filters (in their BOB, GHB, etc.), then you could leave the unused one for the car.

        Otherwise yes, some combo of a coffee filter / some other filter that can remove visible particles + purification tabs are the way to go. (We haven’t done a post on those tablets yet, but they are in BOB/GHB lists and we’ll do a specific post on them soon.)

        7 |
      • Alicia KC

        The Guardian states it can be frozen. Pricy but fits the requirements.

        “Extremely Durable: Engineered to withstand heavy use, freezing, drops*, and harsh environments.”

        4 |
    • Philip

      John, I just discovered this site last night. Wow! Extremely impressed with your work. Newbie question: since I live a block from the sea, do any of these products desalinate as well or should I just focus on that process (which would mostly purify as well)? Any suggestions on desalination?

      7 |
      • John AdamaStaff Philip

        Thanks so much for the kind words, glad it’s helpful! Great question, and one we were just working on the last few days for an upcoming project. Salt water is the only real exception to the standard “use a filter + purifier” prepper setup, as these products don’t remove salt. Desal is the best option, and for many folks that means using evaporation.

        8 |
    • Dan Ello

      Thank you for the great site.  Is it still deemed not generally necessary to purchase a purifier that can handle viruses, in light of the coronavirus?  I want to be sure before I purchase a Versa filter/kit.  And if so, is a pump the best/easiest way to purify large amounts of water?  Without this concern I would opt for the HydroBlu Go Flow Gravity Kit.

      8 |
      • Ef Rodriguez Dan Ello

        Right now there’s no evidence of that anywhere. In theory, it could be transmitted in a water system, but the vectors for that are pretty implausible. A direct quote from the EPA’s page on this topic: “WHO has indicated that ‘there is no evidence to date that COVID-19 virus has been transmitted via sewerage systems, with or without wastewater treatment.’ In short, it’s not a concern.

        4 |
      • Mary Jo Groves Ef Rodriguez

        Actually, there was a recent study (Lancet Hapatology for original article— that not only showed coronavirus in water, but that the amount in the water was a predictor for blooming hot spot of virus.  That is, testing the water downstream of a community for viral load, could predict rise in infections in that community. Further, and not well known, is that covid causes a significant number of people to have what appear to be gastrointestinal infections, without the expected respiratory symptoms. MJGroves, MD

        9 |
    • David Dabney

      Thank you for all your work on this John (et al)! Question: I’ve seen a couple consignment MSR Guardians at my local outdoors shop. Would you be comfortable depending on a used Guardian if there’s no visible damage? Or would you be more confident in using a new but less expensive option? I’d like to get the Guardian eventually but it’s not in the budget at the moment 😀 I guess I could test the water to see if it works, but that would cost more money and I wouldn’t be confident in my results.


      5 |
    • Elizabeth H

      Do you have any thoughts on the Grayl Geopress Water Purifier Water Bottle? I know you said you weren’t the biggest fan of the Ultralight Water Purifier Bottle from Grayl, and I was wondering if you had the same reservations about the Geopress. I was thinking of getting one for my bug out bag and killing two birds with one stone by getting a bottle and filter in one. I have an MSR Guardian, but would like something cheaper to have in my bag. Great article by the way…very informative and helpful!

      4 |
      • John AdamaStaff Elizabeth H

        Unfortunately we’ve not yet had hands on the Geopress. Did you end up getting it, and if so, what do you think?

        7 |
    • Uhlan

      Glad to see the Katadyn Pocket made the short list.  The terms used in the article, “Venerable” and “Built like a tank,” are worthy appellations for a product that’s been my go-to filter since my first backpacking trip as a kid back in the 80s, and that one is still in working order today.

      7 |
    • Lowell

      At the top of the article, you list the following trio as an example “upgrade” mix:

      Upgrade: MSR Guardian pump + HydroBlu Go Flow gravity kit + LifeSaver Legacy bottle = $480

      The MSR Guardian I understand: it has virus protection, high flow rate, and works well for shallow water sources.

      The HydroBlu Go Flow gravity kit I also understand as a complement to the pump, because in situations where you aren’t worried about viruses and water is plentiful or deep, you can filter lots of water with little effort.

      What I don’t understand is the LifeSaver Legacy bottle, or any bottle for that matter. What benefit would this or any bottle add to the Guardian + HydroBlu gravity combo, which combined allows me to tackle viruses and shallow water if need be, but also passively filter lots of water if the situation allows? 

      I’ve already got 38oz of potable water stored in a single-walled stainless steel Nalgene in my kit. If I get the Guardian and HydroBlu gravity, why would I add a filter bottle?

      Thank you for your time and effort as always John 💝

      4 |
      • Alicia Lowell

        I would like to hear John’s response as well. The advantage that comes to mind is speed. Situations may arise where you  need to basically dip and drink on the go.  Neither the Guardian nor the Hydroblu are quick as they need setup and time to pump or flow.  But now that I read the article again, the Hydroblu can be put on a standard bottle – just not any that I have in my BOB.  Hmmmmm.  So really looking forward to John’s response. 

        3 |
      • John AdamaStaff Alicia

        Hola amigos! Such great questions / thinking. The answer will probably be underwhelming 🙂

        The trio doesn’t give you any “scientific” advantage over the duo, since as you said, you can cover all of your main threats with the non-bottles.

        Alicia’s note about being on-the-go is part of the answer. It’s essentially about the form factor of having a bottle, even though bottles aren’t great overall, because once you’ve got the basics covered it’s nice to have something self-contained and portable (which also increases redundancy).

        So the “upgrade” in that sense is not an upgrade in technical power, but in form factor variety and how it enables more more use-cases.

        3 |
    • Lowell

      I just tried my HydroBlu Go Flow Gravity Kit for the first time, and was surprised to find that the valve on the bag is placed along the side of the kit, which means that the bottom ~10% of water in the bag basically sits there if you hang the bag from its top.

      Do y’all have any idea why this is?

      Do y’all just fill it all the way up, wait until it can’t dump any more water by itself, then dump out the remaining water?

      3 |
      • Olly Wright Lowell

        I have a hydroblu filter, but not that particular gravity kit. I wouldn’t try tilting the bag to filter out that remaining 10% because it is designed that way for a reason. 

        My educated guess is that if you fill that bag with lake/pond water, you will be getting some sticks, dirt, and bugs in there with your water. Those will hopefully settle in that lower 10% area and not go through your filter. If the spout was at the bottom of the bag, you would have an entire layer of dirt trying to go through your filter. The hydroblu can filter out that dirt, but it’s easier on the filter to not have to. Just dump and rinse out the bag of the accumulation at the bottom and fill up again.

        Is the gravity bag pretty durable or do you think it can get punctured in an emergency situation?

        1 |
    • Mark M

      Katadyn Combi is the best filter on this list for prepping imho, especially if you live on a farm or the countryside. Water will be extremely dirty in a SHTF situation, and less-robust filters and straws won’t last rigorous use. 

      4 |
      • Olly Wright Mark M

        For particularly yucky dirty water another user on the forum brought to my attention a millbank bag to act as a prefilter. Here’s the link for that post. I’m adding one to my kit because like you said, during SHTF our water sources will get even dirtier with more people using them.

        2 |
      • Mark M Olly Wright

        The Combi actually comes with a pre-filter that goes on the end of its hose, but I just put a coffee filter over it with a rubber band for extra protection and ease of cleanup.

        Not only is the Katadyn Combi a silver ceramic/carbon filter, it is also the hardiest and most durable on this list, bar none. Those pen filters and bag filters may be rated for 100,000 gallons, but they’ll never last long enough to make it past 1/10th of that number in real world use. The Combi was even standard issue to the Swiss military mountain units. There’s a reason why Combis are $200 and Sawyers are $20.

        The drawbacks of the Combi are weight, size, moving parts, price, the fact that it needs a hose, and that it was recently discontinued by Katadyn in favor of the less-effective, $400 Katadyn Pocket (sheesh).

        The silver ceramic replacement filters are expensive. Each Combi filter costs about $100 and lasts for 13,000 gallons; so you won’t need but a few, and deals may be had as retailers sell off their remaining inventory. Every new Combi comes with both a ceramic and carbon filter installed.

        The Combi offers carbon filtration, and in a SHTF scenario filtering chemicals out of the water may be even more important that killing pathogens.

        Even with the drawbacks this filter shines amongst the others.

        3 |
      • Olly Wright Mark M

        That does sound like a good filter and one that would be reliable. The carbon filtration is an additional benefit to improve the taste as well. 

        A Sawyer will make me some clean water, but it’s still going to taste like pond scum… yuck!

        2 |
    • AS

      First, thank you for all of the great information on this site.  I have several different water filters for various hiking/backpacking needs, namely the Katadyn hiker for when I know I will be filtering water (longer trips) and a couple of sawyer minis that we carry in addition to water for emergency backup while hiking/backpacking.  After doing a ton of research in preparation for an upcoming trip in which filtration and purification are desirable, I came upon grayl bottles, which are filters(debris, bacteria, Protozoa), purifiers (viruses), and they also remove heavy metal contamination.  These claims have supposedly been verified by independent labs and meets EPA/NSF/ANSI standards.  They are highly durable and very easy to use.  While the filter life isn’t stellar (65 gal or 3 years, whichever comes first), it seems like the ideal purifier for an emergency situation.  Unopened filters last 10 years. For those of us living in/around cities, one would have to assume some degree of heavy metal contamination and likely viral contamination in streams/run off/parking lot puddles or whatever other water source is available in an emergency.  I wouldn’t want to rely on just filtration in this situation.  I don’t believe all chemical purifiers remove heavy metals either (just P&G as far as I’m aware).  At $90 per bottle and $30 per replacement filter, the cost per gallon is significantly higher than a lot of other filters, but there aren’t many options out there that offer this level of protection.  

      3 |
      • Gideon ParkerStaff AS

        Thank you for your great comment. It’s good to see that you are protecting yourself with a bit of redundancy of carrying a backup Sawyer and not relying totally on the Katadyn.

        Also glad to hear you are enjoying your Grayl bottle filter. We did review the  Grayl Ultralight model in this article and did like the virus and metal protection. However, we have some suspicions about the long term durability with the unique “french press” motion. How long have you used yours and have you run into any issues so far?

        2 |
      • Alicia Gideon Parker

        +1 the here on appreciation for the post and interest in its durability.  I wondered if any of your experience @AS or the TP testing @Gideon included filtering pool water.  That is one large reservoir next door versus the natural reservoir a mile or so away. The Sagan Life filter that works with a Aquabrick is rated to filter 500 gallons of pool water.  It’s definitely not a backpacking option, but looks easy to use in the more likely shelter at home long term scenario.

        3 |
      • Gideon ParkerStaff Alicia

        Alicia, pools can be a great source of emergency water for cleaning, bathing, or flushing the toilet, but because of the chemicals in it, it’s not the best for drinking. Filters that are able to filter out chemicals usually have lower life spans like the 500 gallon Sagan.

        Distilling pool water is a possibility but requires a lot of fuel to get the amount you need. Solar distillation is slow and doesn’t produce very much either.

        Having multiple methods of water collection and treatment is the best way to go. Here’s an example:

        • Use pool water for bathing and cleaning.
        • Use your home storage of potable water for drinking.
        • Have a rain catchment system and filter through a cheaper and longer lasting filter like a Katadyn.
        • Take a trip down to that reservoir once a week and fill up water that will be used just for drinking.
        • Use a small solar distillation system to provide a small amount of clean pool water.
        • Have a Sagan Life Filter as a last ditch resort for treating pool water.
        3 |
      • AS Gideon Parker

        I’ve been using it for 8 months now and have not had any durability issues.  It has been dropped numerous times and other than a few scuffs, its completely fine.  I’m very happy with it and have started taking it as my primary water filter.  The only thing I would suggest is keeping a small zip top bag with it for situations in which the outer shell of the bottle doesn’t easily fit into the water source.  

        2 |
    • Gideon ParkerStaff

      Pasting a note from a reader:

      “Hello, I read The Prepared almost every day. I noticed the review guide on portable water filters states about the Katadyn Hiker that Katadyn says it is not for backcountry use. I just received one I ordered from REI and didn’t see that statement in the manual. I also haven’t seen any such statement online in a quick Google search. The closest thing I saw in the manual was a warning not to use it in brackish water or water with chemical contamination. I suggest checking and maybe correcting your statement.”


      Thank you for your catching that and bringing it to our attention. I reached out to Katadyn and they responded with:

      “…All of our water filters, including the Hiker, can be used in the backcountry.
      And really were designed for exactly that…”

      I have since updated our article to reflect that the Katadyn Hiker water filter is able to treat backcountry water sources.

      3 |
    • Hans

      Thanks for all the great info. I understand viruses aren’t a major threat in US waterways currently, but what are the primary reasons for that (and thus the possibility for change in the future)? If climate change results in more extreme heat/temperatures in the US and/or if the US were to become “less developed” would we expect viruses to be more of a threat? Now that the Katadyn Pocket and MSR Guardian are the same price, debating whether the “tankiness” of the Katadyn Pocket is worth the lack of virus protection.

      2 |
      • AS Hans

        So the primary reason viruses are a threat in underdeveloped countries is because much of their water is contaminated with untreated human waste.  These viruses typically result in diarrheal illnesses, which further contaminates the water supply.  Any place where untreated sewage can mix with drinking water will have the potential to have viral, bacterial, and protozoan contamination.  This is a chronic issue in areas that lack basic infrastructure, but could easily become an issue almost anywhere if a major disaster were to occur.  If your water filter is just for hiking/backpacking in areas with low human population, good sanitation practices, etc, no viral filtration is needed. If you just want one filter that would cover a disaster situation, viral protection would probably be important.  Of course, you can always use chemical decontamination as a backup if the filter you have doesn’t protect against viruses.

        4 |
      • Hans AS

        That’s helpful, thanks!

        2 |
    • underprepraccoon

      Where I live, there’s already a decent amount of heavy metals in the water as it’s mostly deep well water and there are mines all over. I would expect it to get worse if grid down in summer and winter, and extra low water table in winter a la Texas freeze 2021. Everything is in water tanks but I’m not sure how much it’s processed before being put there.

      I’m also not sure if I would trust surface water out here anymore (think Church Rock tailings spill, among other things).

      Ideally I think the Alexapur gravity would be optimal, even for a built set up instead of factory. But like, that capability in a portable package that isn’t an absurd cost isn’t available with lab confirmation. It’s also not portable enough.

      I would like to start with a portable device that would do heavy metals at least, but all the carbon filters aren’t specific about what they can and can’t do.II figure the recommended with the carbon filter, and the PNG purifier of water powder seems to be the only practical solution, but there are also no specifics on the purifier of water capabilities.

      So does the recommended gravity kit, purifier of water mix and just investing in way more water storage seem more realistic?

      I could also use the recommended kit on the stored water if there was any contamination as well. I’m just frazzled trying to find the better solution for what I need and stay in budget, black outs are happening more and I want to round out my preps while I can

      3 |
      • Gideon ParkerStaff underprepraccoon

        Filtering heavy metals isn’t a feature in most portable water filters, but it’s good that you are aware that it is a concern for you and is something you need in your filter. 

        From the article, here are the filters that have some heavy metal protection:

        3 |
      • Thank you for the recommendations.

        After digging into the ones that aren’t bottles, the survivor filter pump and the recommended straw filter seem well enough.

        I couldn’t find any lab test info on the MSR mini works and the life straw only was tested for lead.

        The Survivor pro was tested for lead, mercury and cadmium. While those tests are 7 or so years old now, if it’s still the same technology, it should work.

        It’s not as effective as the Alexapur, but it’s better than everything else for this specific case.

        I also wish I could do my own testing, I have the skill set for it, but not the certifications.

        Might as well not take the risk of something lesser, there’s rumblings the local hospital might close soon, so higher echelon care won’t be as accessible so can’t risk anything lesser.

        Should probably invest more in my medical kit too

        3 |
      • Gideon ParkerStaff underprepraccoon

        Sounds like you have a good plan laid out there. You should do your own testing. You don’t have to be certified to test your own water and know if it is safe for you and your family to drink. 

        2 |
      • Agnes underprepraccoon

        Thanks for the great article.

        I didn’t see a mention of this anywhere on the site, so I wanted to share. The Puralytics Solarbag is tested for viruses, heavy metals, petrochemicals, urine and all sorts of other stuff. Approved by EPA, WHO etc:

        There is a list at the end for all the contaminants it is tested for. It requires sunlight but still works on cloudy days, just takes longer.

        Quote from the linked pdf: “It is the only portable, non-powered water purifier that meets and exceeds the World Health Organization (WHO) standards for a highly protective device.”

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      • Bradical Agnes

        I know the sun can sanitize water left in something as simple as a disposable water bottle or ziplock bag so at first I thought this wasn’t anything special and just a plastic bag with a cap. But when you mentioned that it gets rid of heavy metals, I looked into it more and there is a lining inside the bag that reacts to the sun and breaks down those heavy metals and other chemicals. 

        The bag says it only lasts 500 uses or after 7 years, so that lining seems to break down over time but if the bag stays in tact, it should still be able to kill viruses and bacteria. Cool product. At $60 though and the 7 year shelf life, I would almost want a manual filter that lasts indefinitely on the shelf and filters much quicker than the 3-6 hours this takes to clean 3 liters. 

        Sorry if I’m being dismissive, but just seems like a lot of money for a plastic bag. Do you have one and have used it before?

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      • Agnes Bradical

        No worries. That’s part of the reason why I posted, I was curious about more experienced ppl’s opinions.

        I have one that I currently only use when we have power outages in my area, which happens about 1-2x a year after the winter/summer storms. So no heavy use so far. I live in the city, if anything ever happened to our water supply it would be full of everything you can think of. I didn’t find any filter with a longer list of tested substances, so I liked it as a backup solution. I wouldn’t use it as my sole option.

        I was planning to take it camping this year to do more testing.

        The Malawi study showed that it was good for >1000 uses so ~3000+ liters but that’s obviously still limited. Then again, the MSR Guardian filter is good for 10000+ liters. Price-wise that seems comparable.

        When I was deciding on filters to buy I had read that the MSR filter also has a shelf life of 5 years or so but I can’t find that any more right now. So maybe the info is outdated.

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      • Bradical Agnes

        The SolarBag certainly is impressive with it’s large list of things it has been tested on, multiple pages worth on that PDF! I like how there are no moving parts, extremely lightweight, and dead simple to use. 

        That’s great you have been putting yours to use. I’ve been thinking about the bag all day since you introduced me to it and I’ve been very interested in it.  

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    • Michaël


      Great website, with much useful information!

      My plan is to go cycling and wildlife/birdwatching through everywhere in South-East Asia for more than a year, in Indo-China, Phillipines, Indonesia, etc. The dream is to end up in Papua New-Guinea.

      While cycling in hot weather I drink about 10 liters of water a day. I don’t want to, and in many remote places I wouldn’t even be able to, buy water bottles for all of that. In Europe (and Georgia, Caucasus, where I’m now traveling) I can use my loyal Sawyer Squeeze filter and filter unlimited amounts of water everywhere, both through a big gravity system or squeezing by hand.

      But unfortuntely, the Sawyer Squeeze doesn’t filter viruses out of the water, so it’s only a partial solution for South-East Asia. I don’t know whether it’s possible to buy chlorine dioxide pills/ liquid in many places in South-East Asia and I don’t want to lug around too much. I also don’t like the chemical taste and don’t know whether it’s healthy to use in large quantities for extended periods of time. I could buy a Steripen, but you can treat only one liter of water at a time, you would have to filter the water anyway, and you need to bring multiple spare batteries and possibly another light bulb.

      My main options for now are the pumps Survivor Filter Pro X and MSR Guardian, or electrified chemical purifiers Aqua Research H2gO Prime and the Potable Aqua Pure.

      The Survivor Filter Pro X seems awesome. It produces very clean (0.01 main filter) and tasty (carbon filter) water without effort (electronic). The downsides are that it is fairly bulky and heavy and, I’ll need one or two carbon filters and, most importantly, that it’s an electronic device and I’m a bit hesistant in placing all my trust for clean water for a year into that. A good option would be to order the manual convertion kit with it. So that, if something happens, you can still manually pump. But it will add even more to the weight and bulkiness of the set-up and the flow rate for manually pumping is really low (0.5 l per minute), which means 20 minutes of pumping for ten liters. So, I wouldn’t want to do that for extended periods.

      An alternative would be the MSR Guardian, which is a fully manual pump with an exceptional flow rate of 2.5 l per minute. The downsides are that is is even bulkier and heavier than the Survivor Pro X (without the manual back-up kit), that is has only a 0.02 main filter (compared to 0.01 for the Survivor) and that it is super expensive (almost 400 dollars). It also does not have a carbon filter, so the water will taste less good. Furthermore, there are reports of the pump breaking, which could be a potential disaster and unexceptional for a pump with a price like that.

      In either case, I might still bring my Sawyer squeeze filter, combined with chemical drops, as a back-up system.

      On the other side are the chemical purifiers Aqua Research H2gO Prime and the Potable Aqua Pure. I couldn’t really find a difference between those two. The upsides are that they are lightweight, you only need salt and that it is easy to pair them with my existing Sawyer Squeeze filtration system. The downsides are that it is chemical, so it makes the water taste less good (although better than usual pills). And from a health perspective I also don’t want to drink a lot of chemically-treated water for a year straight.

      I’m still researching and hesitating a lot. I’ll have to make a decision soon, since I’ll be leaving Georgia, Caucasus, in a month and will travel to Thailand afterwards. So, there’s only one more month to let a device ship (from potentially the US) to Tbilisi.

      Thanks for any help/suggestions!


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      • Gideon ParkerStaff Michaël

        That sounds like quite the adventure! I wish you safe and smooth travels and wish I could go with you.

        You have some great questions. Looking at the size of three of the virus filters, the Survivor Filter Pro is smaller and lighter than the Pro X or MSR Guardian. 

        Survivor Filter Pro- Size: 6.5 x 3.2 x 2″ Weight: 12.8 oz

        Survivor Filter Pro X- Size:  6 x 5 x 2″ Weight: 13.5 oz

        MSR Guardian- Size: 8.2 x 4.7 x 3.5″ Weight: 17.3 oz

        I know that the electronic component of the Pro X is nice and hassle free, but for being smaller, lighter, cheaper, and not being reliant on electronics, the normal Pro might be a better option for you with the only drawback being manually pumping.

        The MSR does filter faster but doesn’t filter down as far, is much more expensive, heavier, larger, and doesn’t have that carbon filter. The carbon should take out some heavy metals and make the water taste better. VERY important to have your water taste good, otherwise you won’t be as likely to drink it and will be dehydrated. 

        You will need to buy an additional carbon filter for the Pro or Pro X. They last about 2000L, and if you drink 10L a day and will be gone for over a year, that’s 3650+L. 

        If it were me, I would definitely go with the Survivor Filter Pro, get an additional carbon filter, and bring along the Sawyer Squeeze as a backup filter. Don’t rely solely on one filter the whole trip, if it broke you would be in trouble.

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    • Claire

      What filters would you recommend in both a bug-in and bug-out scenario for viruses (for a suburban/urban scenario where the water way be contaminated with various pathogens after a major natural disaster or attack)?

      What do you think about the Lifestraw Community filter ( for a bug-in scenario? (e.g. lasting >weeks)

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      • Gideon ParkerStaff Claire

        Hi Claire,

        There are a few options for viruses in bug-in and out situations. Just remember that the risk of contracting a virus from water in America is almost zero in normal life. So think about if you really want to go with a more expensive filter that can do that and also sacrifice for a slower flow rate.

        The best portable survival water filters article has many recommendations for bugging out and a recommendation will depend on your budget and form factor desired. For example, there are straw, pump, and bottle configurations.

        For bugging in, the Best home water filter article has recommendations as well. The Lifestraw Community looks like a great product for providing a lot of potable water to many people for a long time, but something like the Berkey tabletop filter as recommended in that article might be a bit more visually appealing to live on your countertop during every day life and also has the benefit of being a carbon filter which will improve the taste of the water.

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      • Alicia Gideon Parker

        I just learned a home-sized Berkey isn’t shippable to California.  They’re working on it.  Their third party testing needs to be blessed or something.  

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      • underprepraccoon Gideon Parker

        I think there’s a possibility this might change, there’s a few pilot programs to start purifying sewer water in Colorado, and with the extreme draught that’s not being mitigated, I could see that happening to a lot more places if the idea takes hold and grid go down

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    • Claire

      Hi! Do you have recs for a water filter that you would attach to a faucet in a (longish term) bug-in scenario?

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      • Carlotta SusannaStaff Claire

        Hi Claire, you might be interested in these forum posts:

        Whole house water filtration system

        Under-counter water filters

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      • Claire Carlotta Susanna

        Thank you! In buying a whole-house water filter, what are the things I should look for it to filter out (eg VOC, cloudiness, etc)? I’m a little overwhelmed! Don’t know if I’m looking for a whole house filter to filter out the same stuff as say a Berkey’s. I live in the suburbs. I want to filter the water for overall health but also want one  in place for shorter and longer term disaster situations. 

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      • Carlotta SusannaStaff Claire

        Hi Claire, we’ve obviously been corresponding via email since this message and I wrote to you that no matter if you choose a faucet or whole house filter I would still recommend having a separate backup filter (be it an inline portable filter, a Berkey, etc) in case you can’t get water out of your main pipes. But as for deciding if to get a whole house filter it really depends on your priorities: if you want to filter water for “overall health” then both a whole house filter or a Berkey should do. On top of my head, I think that a difference is that a whole house filter should be able to filter out microplastics, while I’m not sure if a Berkey does. Just keep in mind that microplastics are everywhere now and, not only do we drink them but we also inhale and ingest them all the time. Not trying to steer you in any direction with this, just wanted to reiterate that it depends on your priorities.

        FWIW I live in the ‘burbs as well and right now the only worry we have is that during the summer months, they put more chemicals in the main water supplies to offset the risk of algae that keep popping up in our reservoirs. The water is perfectly safe to drink from the faucet but it tastes a bit of chemicals so we use the Berkey on a daily basis to just improve the overall flavor. We are not thinking too much about microplastics now. We don’t have a whole house filtration system right now because we are happy with the Berkey, which doubles down as an emergency filter, too.

        Having said that, my in-laws live in the mountains and get their water from a well so they actually do have a whole house filtration system but that’s because the burden of treating the water is on them, rather than on a city’s municipality (and they also have spare portable filters as a backup). I’ve also seen posts on social about people living in cabins and getting their water from a creek and just using a Berkey.

        Unfortunately, I can’t really comment on which brand or type of whole house or faucet filter is best; if you have any more specific questions you can ask them in one of those forum posts I linked above, or create a new forum post altogether.

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