Review: CrazyCap2 Ultraviolet Water Bottle

Ultraviolet light is one way to treat potentially-harmful water. There’s a growing market of reusable water bottles with UV built into either the cap or body. The folks behind the CrazyCap Gen2 bottle sent us one for review (which, as always, never impacts what we say.)

The CrazyCap2 is a system of water purification with a UV light built into the cap of a reusable water bottle. With a quick tap on the cap, the UV light shines for either 60 or 120 seconds, depending on the level of purification needed. CrazyCap offers a kit containing the 17oz bottles with the in-built UV light cap for $69, the cap on its own for $59, as well as few accessories such as extra chargers, carabines, handles, and gaskets.

The size of the cap is 34mm in diameter, and fits 9oz, 12oz, and 17oz cola-style bottles as well as a 15oz bottle of S’ip by S’well.

Here’s what you need to know:

  • The punchline is that, while it probably does it’s job fine and it would be a decent EDC companion for general water quality, it’s not something you would use for a real prep.
  • I’m suspicious of open-top water bottles due to cleanliness, so that’s not a great start for this system for preparedness.
  • The CrazyCap2 sterilizes water in only 60-120 seconds (depending on your water source), and it’s effective in killing protozoa, mold, bacteria, viruses, or other harmful pathogens.
  • The UV light has an ‘auto-off’ function that’s helpful if you don’t want to waste your battery.
  • The CrazyCap2 also has some design features that makes it hard to use.

More on water filtration:

First impressions

The CrazyCap2 kit includes almost all the products and extras you can buy from CrazyCap (unless you really want a silicone handle instead of the silicone carrier with carabiner clip). The box comes with:

  • 17oz insulated stainless steel bottle
  • UV Led cap
  • Charger
  • 1 x silicone carrier with carabiner clip
  • 2 x extra silicone gasket seals
  • 1 x individually wrapped alcohol wipe
  • A canvas storage bag

The extra silicone gasket seals can be useful because if the one that comes with the cap breaks down with use, you have spares handy. Extra gasket seals on hand mean you don’t need to wait for a delivery. The carabiner carrier is also nice to have in case you want to attach the bottle to the outside of your BOB, or any bag, freeing space inside. The alcohol wipe allows you to disinfect the rim of the bottle before starting to drink from it, and is a nice little touch in these pandemic times.

I don’t see the usefulness of the canvas storage bag, though; once you start using your bottle, you are not going to store it away. So in my opinion they could have swapped the bag for two extra gaskets.

Design flaws in the cap

For a purification water bottle, the CrazyCap2 has a surprising defect built into its structure. Between purification and drinking, it’s possible to recontaminate your water. That’s because of a puzzling choice CrazyCap made when designing the bottle.

When I opened the box, the first thing that I noticed was the mouth of the bottle. Like a Swell or Nalgene bottle, the CrazyCap2 has an open mouth. It doesn’t have a nozzle or a straw coming out of it to control exposure to dirt.

From a health and safety perspective, that open mouth is a big no-no. I typically look for bottles with tight drinking nozzles that seal water off from the outside world. With an open mouth, there’s too much room for contaminants to get in, and you expose your water every time you open the bottle.

Even worse, the cap locks tightly around the bottle’s open mouth. Grime from the outside world that’s trapped under the cap can then make direct contact with your mouth. Studies have shown this cap-mouth contact can lead to “bacterial contamination unless washed regularly.” Gross.

I am so opposed to open mouths that I had a hard time drinking out of the CrazyCap for this trial. Although I tested the bottle at home in a relatively clean environment, I still refused to drink directly from the bottle. Instead, I just poured the water into a glass so I didn’t have to touch my mouth to the parts that had touched the cap.

It’s unfortunate that CrazyCap made the open mouth a central part of the design. There isn’t an easy way to work around the recontamination. The cap (and therefore the open mouth of the bottle) is what contains the UV light for purification. So if you wanted to replace the open mouth with a tight nozzle or straw system, you’d lose the UV light, which is the whole point of buying the CrazyCap system.

Another design flaw: there’s a very narrow space (5mm –  a little over 3/16 inch) between the UV light and the outside of the cap, which is where the bottle mouth goes when you close the bottle. That narrow space is very hard to clean. I wasn’t actually sure how to clean it, so I reached out to CrazyCap. Representatives from CrazyCap said the cap can be “lightly washed with soap and water.” But if you want to do a good job cleaning inside the cap, you’ll probably need some kind of a narrow brush to clean it (like a straw cleaner).

The gap flaw is actually a huge deal when you imagine using the CrazyCap in a survival situation or while camping away from clean, running water. You’d probably need to gather water from a pond or a puddle. Scooping up the water from the pond, you’d get the mouth of the bottle all dirty and recontaminate the mouth and cap. And because the mouth sits in the gap, it wouldn’t even be cleaned by the UV light. Instead, it would just contaminate the cap and trap dirt up there. You’d recontaminate the open mouth every time you closed the bottle until you could get soap, clean water, and a narrow brush.

Again, no thank you.

Steel bottle body

The bottle itself is a nice insulated stainless steel bottle with a heavier bottom for stability. The cap is also stainless steel. The touch pad that controls the UV light is flush with the cap,and the actual UV light apparatus is just inside.

The cap we received from CrazyCap for review had a mechanical imperfection and didn’t screw flush to the bottle. Still, it seems solid. To test the seal, I filled the bottle with water, swished it around, shook it, and left it upside down for 24 hours. Despite the imperfection, the bottle didn’t leak. In this case, the mechanical imperfection doesn’t compromise the bottle’s overall function.

Charging for use

Before using the bottle, the cap needs to be charged for about 4 hours. The charger is a goofy cap that covers the UV bottle stopper and charges via standard USB. I say goofy because it seems unnecessary to have a plastic charger that covers the whole cap when the charging spikes are so small and are positioned only on one side of the charger.

Disappointingly, because the charging spikes are on one side, the charger sits tilted on top of the cap, another mechanical flaw that however does not affect its performance. CrazyCap probably could have used a magnetic charger instead. The charger is made of hard plastic and, although I haven’t mistreated it, it seems sturdy enough to survive at the bottom of a laptop bag. In case you need to replace it, it’s only $8.

The purification process

The UV light has two purification modes to choose from. If you’re using tap water or water from a fountain, tap the top of the cap twice to turn on the UV purification. If you’re using water from a lake, pond, or river, you’ll need five taps to purify properly. A blinking blue light appears on top of the cap when the UV light is set off and, once the purification cycle ends, it will turn into a solid green light.

I found this system to be a little unpredictable. The taps do not always set off the UV light straight away, and I often had to try multiple times before the UV light turned on. The whole process takes only 60 seconds for tap water and 120 seconds for natural bodies of water.

For my first try, I filled the bottle with tap water, purified it, and drank it. Simple enough, but my water at home is very chlorinated. Even after the correct purification time, it still tasted like chlorine. The chemical taste put me off and I decided not to drink from the CrazyCap bottle anymore.

Thoughtful features

The UV light automatically runs a cycle every 4 hours. That cycle is meant to keep your bottle clean and free of mold even when not in use. I’ve left the bottle with just a little bit of tap water inside for a whole week and when I opened the bottle there was no moldy odor whatsoever.

Even CrazyCap’s website admits that the UV light alone is not enough:

“Washing your reusable water bottle frequently is the most important thing. Keep the black mold at bay with a thorough wash every 5 to 7 days, fill the bottle with boiling water and vinegar [especially the metal water bottles], and sink overnight in the water + vinegar mixture at least once a month.”

In a survival situation, it would obviously be unrealistic to think that you could wash your bottle with vinegar and boiled water every week. But the UV light in itself is already a big advantage in keeping your bottle sanitary.

Another neat feature of the CrazyCap: you can use the UV light to sterilize objects you’re worried might be contaminated with COVID-19. Just unscrew the cap, tap the UV light, and pass the light over the object you want to sterilize. As we explained in our packages disinfecting post, it is not clear how long it takes for the UV light to disinfect an object. Also worth noting, if used on hands, UV light can cause skin irritation. (We recently reported on far-UV-C lights that could disinfect surfaces without hurting people. But this isn’t one of those lights.) So to me, the ability to disinfect phones and other small objects with the CrazyCap is a plus, not a main feature.


  • Quick sterilization time
  • The UV cap fits other cola-style bottles so you don’t have to buy the whole kit if you don’t want to
  • UV light can be used to sterilize objects too (although do not depend on it)
  • Nice stainless steel insulated bottle


  • Open mouth bottle, meaning that you will introduce pathogens to the water every time you drink from it, or when you scoop up water from a pond, stream, etc
  • 17oz is not big enough for survival purposes
  • Insulated, so you cannot boil water in it, if you need to
  • Inconsistent activation of the UV light

Our final verdict: Might not be worth it

In total honesty, I was disappointed by the CrazyCap2. Even though they market the bottle for outdoors use, it’s not actually made for survival situations. The open mouth is the biggest disqualifier. After reading enough scientific studies about water contamination and open mouth bottles, we just can’t endorse this bottle for a prep.

CrazyCap Gen2

CrazyCap Gen2

We hesitate to recommend this product for survival situations, though it could work for everyday use and we admire the ambition of UV decontamination.

After years of hiking and backpacking, I learned never to use a bottle that doesn’t have a straw or a nozzle on (or to pour water into your mouth without touching the bottle neck, but that’s a different set of skills). The mouth just gets dirty and you couldn’t even use it to safely flush a wound.

The only instance I could feel confident in using this bottle is if it was sitting on my desk, providing that my office (or home, nowadays) didn’t have too much chlorinated water. But I wouldn’t even bring it with me on a commute or keep it as my everyday carry bottle, for the same reasons as above.