Introduction
The CrazyCap 2 ($59, 1.9 oz/56 g) is an ultraviolet water treatment device that takes the form of a bottle cap. At first glance, this little multi-use item seems like the perfect invention for ultralight backpackers on the go. But how does it perform in the field with its bottle compatibility issues?
The Test
Inside the box, I found directions, a warning about not looking directly into the UV light, an alcohol swab, a USB charger, and The CrazyCap 2. Aside from being double the weight (0.85 oz/24 g vs 2 oz/56 g) than a standard S’well water bottle, the cap is pretty similar to a standard S’well lid.
The CrazyCap 2 lid requires a specific bottle format and you will require either a CrazyCap bottle, S’well bottle, or another similarly configured bottle. I used a Manna water bottle. I did find a cola style water bottle in plastic (2.8 oz/80 g) (also made by Manna), but because plastic has a different screw style than the stainless steel bottles, the CrazyCap 2 didn’t fit.
Touch once and the CrazyCap 2 lights up and give the battery status, touch twice and it does a normal sterilization mode (one minute), touch five times and it gives the crazy sterilization mode (2.5 minutes). Indicator colors red for less than 25% battery, orange for 25-50% battery, green for a full charge, and blue for sterilizing in progress.
The charge mounts overtop the cap and plugs into any USB port, including one on a laptop or battery pack.
The Limitations
The Crazy Cap 2 is a neat product but is a limited use item for most ultralight or lightweight backpackers. The first obvious issue is that The CrazyCap 2 uses a stainless steel bottle which is heavier than most of us would be comfortable packing around if only to protect our “ultralight cred.” I’m all for finding little luxuries on the trail and if a stainless water bottle is yours, this is a fantastic product. For me, a fancy water bottle is definitely not one of my luxuries.
Second, the battery life on The CrazyCap 2 lasts about a week doing 5 batches of 17 ounces (0.5 L) or 85 oz (2.5 L) of water per day or 595 ounces (17.6 L) per week. This is great on a short trip with low hydration needs. However, on a longer trip, charging may be required, which therefore requires the addition of a charging pack (or two.) Obviously this is a limitation but not a real strike against The CrazyCap 2. If you are bound to using UV technology, battery life will be a constant factor. A Steripen Ultra has about 1,700 ounces (50 L) of water per charge or 170 ounces (5 L) per day for 10 days. The Steripen Ultra weighs about 4.9 ounces (138 g) vs CrazyCap 2’s 1.9 oz (56 g), but the Steripen Ultra also processes twice as much water per week and lasts an additional three days.
This brings me to my third point. After I started using hydration packs because I like them more than bottles, I didn’t use my Steripen Ultra very often. When I finally dug it out to sell it about 5 years after it had last been charged and put away, the battery was still at ¾ charge. The LCD screen still had its idiot-proof interface. I could use the Steripen Ultra instantly and explain how it works to the guy who bought it. The CrazyCap 2 was less intuitive, in that the button is glitchy with a 3-second delay between touching the button and it responding. The delay makes you second guess if you are using the CrazyCap 2 correctly. I found myself asking, “Is this thing even on? Or does it need to be charged again?” The CrazyCap 2 indicator colors (red, orange, green, and blue) all make sense, however, what it does not do (unlike the Steripen Ultra) is give a reading if the water is too contaminated or if the sterilization failed. The Steripen Ultra has a happy face, a sad face, an error, and a battery life indicator on its LCD screen, and its neoprene carry case has a definition for each icon.) A sterilization failure indicator seems crucial for any device you plan on using to keep you safe from giardia.
The CrazyCap 2 can be used multi-functionally for sterilizing other items, and this is good in theory. It’s true, a UV light can be used for sterilization, however, it is important to note that UV Sterilization only works if the light is not impeded. By not impeded I mean the surface has to be clean, with no particulates covering the surface. The requirement of surfaces to be clean is why hospitals don’t extensively use UV sterilization technology. This is also why cloudy water doesn’t work with a UV light, as the particulates block the light and the sterilization fails. In short, this is a great device if you know you have crystal clear water. UV sterilization is a recipe for disaster with cloudy water. With the CrazyCap 2 providing no notification it failed sterilization in cloudy water, it makes me wary of using it on long trips where I have questionable water sources.
Another potential issue is that CrazyCap 2 is relatively expensive. The cap itself is $59.00 plus a compatible bottle at $25.00 – $45.00. A Steripen Ultra is $110.00 and a Steripen Ultralight is $90.00. Having used both types of products, I would pick the Steripen Ultra. The Steripen Ultra can pretty much be used in any water bottle, and overall I found it more reliable than the CrazyCap 2.
My final issue with the CrazyCap 2 is this – every time you fill the bottle in a water source, you have to sterilize the mouth of the bottle. The mouth of the bottle must either be sterilized before you screw the cap on so you don’t cross-contaminate the cap’s threads, or you must sterilize the mouth of the bottle every time you take a sip. CrazyCap provides one alcohol swab for this purpose. On a long backpacking trip, a single alcohol swab would be insufficient. Carrying one alcohol swab for every water bottle refill or every sip is impractical, to say the least. Therefore, you could use the CrazyCap’s UV rays to sterilize the mouth of the bottle but at a battery cost of 1 use per every 17 oz (0.5 L) of water sterilized, which cuts the battery life down to 3.5 days. The other possibility, of course, is to take a weight penalty and carry a small bottle of alcohol or bleach with a small cloth to wipe down the mouth of the bottle. Obviously, this is an issue with other UV systems as well, but the Steripen markets a bottle mouth cover for filling the bottle. This could be a solution for the CrazyCap as well but to my knowledge, no one is making a bottle mouth cover for cola style bottles.
Conclusion
I love the idea of the Crazy Cap 2, but its limitations concerning the bottle size and type mean that its functional use in my pack is limited. From an ultralight perspective, the best use of CrazyCap 2 is for a short duration trip with excellent water sources. I would gladly use the product for a mountain marathon where water sources are frequent and clean, gear is minimal, and the duration is short. At this time, however, the use of the CrazyCap 2 is primarily for people who have a sentimental attachment to a specific S’well style bottle regardless of its weight. If CrazyCap produces an ultralight bottle, or comes up with more universal designs, and addresses the mouth sterilization issues, then I can see greater use for this product in the future.
DISCLOSURE (Updated April 9, 2024)
- Product mentions in this article are made by the author with no compensation in return. In addition, Backpacking Light does not accept compensation or donated/discounted products in exchange for product mentions or placements in editorial coverage.
- Some (but not all) of the links in this review may be affiliate links. If you click on one of these links and visit one of our affiliate partners (usually a retailer site), and subsequently place an order with that retailer, we receive a commission on your entire order, which varies between 3% and 15% of the purchase price. Affiliate commissions represent less than 15% of Backpacking Light's gross revenue. More than 70% of our revenue comes from Membership Fees. So if you'd really like to support our work, don't buy gear you don't need - support our consumer advocacy work and become a Member instead.
- Learn more about affiliate commissions, influencer marketing, and our consumer advocacy work by reading our article Stop wasting money on gear.
Discussion
Become a member to post in the forums.
The CrazyCap 2 ($59, 1.9 oz/56 g) is an ultraviolet water treatment device that takes the form of a bottle cap. At first glance, this little multi-use item seems like the perfect invention for ultralight backpackers on the go. But how does it perform in the field with its bottle compatibility issues?
Interesting that there is no claim that you need to stir, shake, or otherwise agitate the water, as with the Steripen, to make sure that all of the water gets within range of the light.
Is there some difference in the strength of the UV light, or is Katadyn just being more cautious?
I really appreciate the way you highlighted the pros & cons! Thank you.
Thanks for the review,
Just a clarification, in the last photo you have the device purifying water – do you mean that it filters the water as well or did you mean sterilising? The two are different processes.
If a biologist with relevant credentials is handy I would be curious to know if it is actually necessary to disinfect the bottle thread. To my knowledge, getting ill from a waterborne disease requires a large enough pathogenic load, not a zero pathogenic load. For example, our water supply in western countries is not free of pathogens, just has low quantities.
My point being if the 1 litre of water is sterile but a small amount of contamination is gained from the bottle thread – is this sufficient to cause disease?
On the steripen – I found it highly, highly unreliable, Maybe an older model but it refused to work at times and last i read it was due to the two probes being wet (!) when using. Anyway this seems like a positive step towards reliable UV water treatment so long as you can find a practical bottle to fit.
Infectious disease takes over in your body when replication of the pathogen inside the body overwhelms the immune system’s ability to eradicate it. That’s the general principle, although it’s more complicated than that of course.
Think ‘whack-a-mole’.
It’s easy to whack one mole that pops up now and then.
It’s harder to whack 7 moles that are simultaneously popping up all over the place.
So initial dose is important. If the initial dose of pathogens is low, the immune system can whack ’em.
Same reason why wearing a face mask helps minimize the transmission of airborne respiratory diseases – they decrease the load of pathogens that can be transmitted to others.
Back to the question.
Is there a high enough “dose” hanging out in the threads of a water bottle to cause an issue?
Depends on how contaminated the water is.
For most backcountry mountain streams, I’d say no.
If I was drinking out of a stock tank, I’d rinse the threads.
Interesting, I discuss this issue in another thread on the Larq water bottle. We had a long discussion about this concept in my New Product Development and Ethic class. The fundemamental problem is what is being claimed and how does the customer really use the product.
The weak link in the design is that the dirtiest part of the bottle will be the mouth of the bottle where people’s lips will come into contact with the bottle. That area is NOT exposed to UV light , it has to be cleaned by the customer. Since there are metrics or verification that this occurs, what they can “claim” is pretty minimal. The water in the bottle may become free of bacteria, however; you cannot say that the bottle is free of bacteria. That would be misleading. My 2 cents.
Doing a few measurements with my highest resolution scale, I can get about 0.2 grams of water clinging to a bottle cap. A similar amount on the bottle’s threads, would be 0.4 grams total that would be un-treated by UV (or chemicals) in the main volume of the bottle.
So 99.99% removal in a 1-liter bottle becomes 99.95% removal. 5x greater bacterial/viral dose.
While 99.999% removal becomes 99.959% removal. A 41x greater dose.
Back when I was mostly using iodine treatment, after it was mixed, I’d crack the bottle cap and let halogenated water flush the threads so that it had the same exposure treatment time. Why not? It was quick and easy. With UV treatment, one could 1) wipe the inner and outer threads dry to remove that small volume of water and/or 2) invert the bottle to flush the threads with treated water.
Pity they didn’t use a standard wide-mouth Nalgene 1-liter bottle cap as the basis of the device. Not the most UL choice but far lighter than that SS bottle and vastly more common. Or, better yet, something that could insert into a Gatorade, SmartWater or standard soda bottle thread.
EliN: Yup, odd about the lack of instructions to agitate. An independent test of SteriPens in wide, middle- and small-mouth water bottles, with and without agitation found, “The SteriPEN® reached a mean reduction of more than 99.99% of bacteria and 99.57% of the spores when applied correctly. However, the results of the trials without agitating the water only yielded a 94.98% germ reduction.”
Source: https://www.sciencedirect.com/science/article/pii/S147789391500174X
The CrazyCap UV LEDs probably need a bottle with a reflective interior to achieve decent water sterilization in a reasonable length of time and energy use. Wouldn’t get that reflection in a standard plastic bottle. Maybe reflections make up for not stirring?
UV LEDs still have a ways to go to match what Steripen does today with evacuated mercury-primed glass tubes.
— Rex
I thought shiny metal surface would bounce UV around like they do Visible and IR. My BIL (first person to entangle more than 2 photons and only to find an exception to the Heisenberg Uncertainty Principle; i.e. a guy who knows his photons) said, nope, very few surfaces would be reflective of UV-C. I had asked about aluminum and SS bottles and (my SUL pipe dream) a potato-chip bag.
His response in full:
The steripen emits UVC. It seems to peak at a wavelength of 254 nm, which is quite short. Most materials will absorb this, not many will reflect it. Any conductive material will stop strongly reflecting at sufficiently high frequency, related to the density of electrons in the material. This is why x-rays go through everything, including good conductors like aluminum. Shorter wavelengths of course have higher frequencies, so materials (like metals) that are good and shiny for visible wavelengths may not be for UVC. Here is some data from the Edmund’s Optics catalog:
I would look at the “protected aluminum curve” and conclude that Al itself stops reflecting pretty close to the 254 wavelength. You might find that it reflects a portion of the lamp’s output spectrum. Note that the UV Enhanced Aluminum has a multilayer dielectric coating that is doing the reflection at the short wavelengths. not an option outside of optics contexts. The potato chip bag is aluminized mylar, if I’m not mistaken. I have no idea how much mylar is required to absorb UVC, but I would guess a double-pass through a potato chip bag would also cause a lot of absorption. This is from a google images search. Looks discouraging.
You might, I suppose, get a decent reflectivity from undyed anodized aluminum. The anodizing produces a porous coating of alumina, which has the same absorptive properties as sapphire, which is transparent down to 225 nm or so. The multiple scattering in the alumina layer would reflect some of the light back, in the same way that snow reflects back visible light. For your ultimate goal of providing safe water, however, the porosity of the coating might be a problem if it provides a home for bugs to live in.
My water purifier of choice is the AquaStar Plus – It’s a UV tube that fits on a standard Nalgene bottle:
It uses 2 CR123 batteries and gives about 60 liters on a fresh set of batteries. At 8.5 ounces (for the bottle, the UV tube/cap, and batteries) it’s the heaviest thing I carry outside pack/shelter/sleeping, but it’s worth it for me to get a liter of drinkable water in 80 seconds.
Sadly, the company sold out to Camelbak so the AquaStar Plus is no longer available.
Call me a Luddite, but that thing looks absolutely useless.
I wonder if an adapter to convert the threads on this to a lighter bottle could solve the issue of the contaminated threads. You could unscrew the cap/adapter combo from the bottle to add unsterilized water, and drink only from the end of the adapter that attaches to the cap.
@davidinkenai thanks for the graduate-level education in UVC reflectiveness. IIRC, another UVC LED water treatment maker insisted that a reflective bottle was necessary, but maybe that was just marketing (photon) spin.
— Rex
It turns out the s’well/manna cap fits very snugly into a Lifeway kefir 1L bottle (1.6oz with cap on my scale), though doesn’t screw on. When shaken hard, some tiny drops come out, but the cap stays firmly put. No water comes out if the bottle tips over. I wonder if this could be a reasonable solution.
I would suspect it would be workable solution, not ideal because it doesn’t seal but workable. I checked around locally and can’t get that brand of bottle so I can’t test the theory.
I do try not to use single use plastics for my water because of the possibility of the plastic breaking down but that’s a personal choice on my part.
As for the question of agitation, I thought the same thing but it’s not included in the directions. It’s either because the light is on longer or it’s related to the bottles reflectiveness as suggested. In the latter case, I suspect switching to a non-metal bottle would be no bueno. I have sent a question to the manufacturer and I’m awaiting response still.
More or less, I stuck this little guy in my pile of failed experiments and went back to my favorite water treatment solutions (Platypus). Hence I forgot the check for questions till now… 😐 my bad.
Become a member to post in the forums.