CrazyCap LED Water Purifier Review

[Backpacking Light]

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?

• CrazyCap LED Water Purifier Review

[Eli N]

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?

[todd]

I really appreciate the way you highlighted the pros & cons!  Thank you.

[Sean P]

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.

[Ryan Jordan]

…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?

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.

[Jon Fong / Flat Cat Gear]

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.

[David Thomas]

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.

[David Thomas]

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

[Rex Sanders]

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

[David Thomas]

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.

[Kevin Babione]

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.

[Todd T]

Call me a Luddite, but that thing looks absolutely useless.

[Edward Barton]

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.

[Rex Sanders]

@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

[Edward Barton]

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.

[Emylene VanderVelden]

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.

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