article debating water treatment effectiveness

[wayno]

To achieve its claimed ability to remove pathogens, water going into CamelBak’s new UV purifier must first be cleaned by a filter from a rival manufacturer. And that rival product is cheaper. That’s according to CamelBak’s own lab testing. And its not the only water treatment technology that’s incapable of performing as claimed.

http://indefinitelywild.gizmodo.com

[icefest]

Working link:
http://indefinitelywild.gizmodo.com/uv- ... 1704387492

[wayno]

hmm, that link was a problem too
lets try again go to the main website page and you'll see the link to the article http://indefinitelywild.gizmodo.com

does bushwalk osbsure the profanity in the correct link title for sensorship reasons?

[Orion]

Apparently it does.
But with a bit of trickery it is possible to fix this particular instance.

Here is the link:

http://indefinitelywild.gizmodo.com/uv-water-purifiers-are-bullshit-and-so-are-some-filters-1704387492

[GPSGuided]

Great article! Long suspected of those durability and efficacy claims.

[Mark F]

On UV filters I don't think he is identifying anything new. Steripen have always been pretty upfront about their use with dirty water. Their instructions get you to stir the light pen in the water helping maximise the likelihood of uv light impacting on all the water. They also recommend pre-filtering and doubling the dosage for dirty water.

The Camelback design placing the UV lamp in the neck of the bottle is I think a serious failing as agitating the water is less likely to achieve a uniform application of the uv. The effectiveness of the uv is a combination of the distance of the UV source from each water molecule, turbidity reducing the effective distance and power of the uv lamp.

I was more surprised by the filter results which I find disturbing. Also, while promoting the use of chemicals he doesn't acknowledge they suffer from extended time needed to achieve their purification effect and issues about increased dose requirements in turbid water.

I will continue to carry my Steripen with a few puritabs as backup.

[GPSGuided]

Good interpretation there Mark!

On the filters, I am not surprised at all by the findings. Those Sawyer and similar filters are effectively ultra-thin membranes that have been used by haemodialysis machines for decades where they are used as single use cartridges. Given the potential dirt/bacteria/fungal growth in one of those cartridges and the physical damages those growths can make, it's hardly surprising. I think the take home message is, give them good flushing and 'disinfection' after each trip and be prepared to discard them at reasonable intervals. I like the sequence of filter + Steripen for peace of mind.

[Strider]

Sawyers instructions are to backflush and then to run 1L + 1 tsp bleach through the filter after each period of usage.

[keithy]

Interesting article, but saying that UV Water purifiers are bulls**t in the title seems a bit like over sensationalisation.

Further down the article, they say

What the All Clear and other UV purifiers can do that most filters can’t is kill viruses. But only once the water is clear enough for the light to reach them. Viruses aren’t actually a huge issue for most outdoor enthusiasts. At least not here in North America. It’s really only if you’re traveling in third world countries that you should worry about Hepatitis A, Norovirus and other viruses.

"Viruses aren't actually a huge issue for most outdoor enthusiasts. At least not here in North America." That shows the authors limited scope of intended audience. He says at the end "Or, just do what the CDC recommends and bring any water to a roiling boil for at least one minute. That kills everything", but seriously when you boil turgid murky, still pond water, it will end up with a hot mucky pond water soup if you don't use a filter before hand.

As MarkF mentioned, the UV doesn't work well in turgid/murky water (because science). I understand if the article's author taking umbrage with the Camelbak marketing department claims of "purified water everywhere", when it should most likely be something like "purified water from clear water sources everywhere". But the article title really seems over-sensationalising.

The Camelback design placing the UV lamp in the neck of the bottle is I think a serious failing as agitating the water is less likely to achieve a uniform application of the uv.

I think the Camelbak UV instructions were to invert the bottle after a given time, while agitating it as well to get more UV penetration. I also agree that a steripen type tube inserted into the bottle probably gives larger surface area contact with the water.

I will continue to carry my Steripen with a few puritabs as backup.

I will do the same for my non-north american hiking travels.

[GPSGuided]

I am not so concerned about highlighting the limitations of UV sterilisation. That's a known physical entity and one the user can easily judge. The real worry is with those filter systems as there's no telling when the physical barrier has failed. I doubt there'll be many out there who can run microbial cultures on a regular basis to verify.

[Allchin09]

I was hoping that the humble water boiling method would get a mention

[icefest]

I think I can guess your preference, GPSG...

AFAIK, the reason they are single-use in dialysis is more due to contamination risk and sterilisation cost.

[GPSGuided]

What is my preference? Not sure I know myself.

Single use in medical equipments is also an issue of liability.

[icefest]

Not sawyer filters.

[GPSGuided]

Wrong!

Have and use a Sawyer Mini. The article just allows one to know the practical limits of one's tool. That's a good and important thing.

[icefest]

I decided to do a more more reading about it and found sawyers rebuttal. What do you think about it?
https://sawyer.com/wp-content/uploads/2 ... -Paper.pdf

[GPSGuided]

Thanks for getting into more detail there Icefest. Given that we depend on this nifty piece of equipment, it's important to know the facts and adjust our use accordingly.

For a start, I am a bit confused by this PDF write up by Sawyer as it would seem the referenced Tuft study (see link below) still confirmed the fouling of those hollow fibre filters over time. Not sure which is the 'Bolivia study' and which is the study that supported Sawyer's current claim. Honduras study or another? Further, I am not sure whether the study was carried out independently. What's reassuring is that the level of fouling was following 23 mths of household use in a developing country. Either way, it's not likely to have filtered 1 million gallons in real life (100,000 gallon claim on the Mini). I am sure that there'll be a laboratory condition where one may achieve 1 million gallons of filtering, but how many of use use our Sawyer in an ideal environment? I also note that freezing voids Sawyer's warranty when encountered after use.
http://whconference.unc.edu/files/2014/10/murray.pdf

I'm also interested in your take on these and if they will alter your use of Sawyer.

Did a search on Sawyer in Scientific Citation Index and found nothing. Do you know what's the exact filtering material used in those Sawyers? Might gain more information by searching for the material than the commercial product.

[Gadgetgeek]

I'm not a huge fan of sawyer, just since their marketing is smelly to me. But whatever, no filter is magic. I like my mini-works because I know what it can handle, and I know the field maintenance. Like any other bit of gear, if you use it wrong, it isn't going to work. Not sure that is a downside, unless the item is nearly impossible to use, or its use is unsuited to the need. A 20l sand bucket would make a decent filter. not really packable.