Sub-zero water purification

[Andy BB]

I must admit to having a bit of a problem with this. The main reason is that most water purifying machines make a very specific point about not allowing the water filter to freeze, as it effectively wrecks it - Sawyer being a prime example. And in continuous sub-zero conditions, that is going to be an ongoing risk, no matter how careful you are.

My solution in the past has basically been to rely on boiling snow - or occasionally breaking through the ice to gather water which is then also boiled. I suppose I could also use a water purification tablet, but haven't done so as yet.

I'd be really interested in your solution to this.

 

[Twodogs]

collect clean snow and boil that seems to be all you can do

 

[Teepee]

There are other options to just boiling;

Rolling boil
Fast boil
Double boil
Extreme simmering

Millbank bags work OK if it's just below freezing or warmer to get rid of lots of debris but are a pain.

I've lost 3 purifiers to icing now-;last one froze in a jacket pocket.

 

[Jared]

UV method maybe? Still would have to melt snow, but not have to bring it to a boil.

Also are activated carbon filters less affected by freezing? Ceramic filters rely on physical size rather than chemical adsorption.

 

[Andy BB]

There are other options to just boiling;

Rolling boil
Fast boil
Double boil
Extreme simmering

Millbank bags work OK if it's just below freezing or warmer to get rid of lots of debris but are a pain.

I've lost 3 purifiers to icing now-;last one froze in a jacket pocket.

I use a three-minute rolling boil as a minimum - can't quite remember why now!

Which purifiers have you lost to the cold? Be useful to know with regard to Jared's point.

 

[rik_uk3]

You need to melt the snow/ice so really I suppose as Cliff says, heat treatment is the way forward (heat to over 70c to kill jimmy germs).

I've not used these for real, just played in the garden with them but they filter faster than a Millbank bag and if you look on youtube there are various mods shown

http://www.ebay.co.uk/itm/18-FILTER...842?pt=LH_DefaultDomain_3&hash=item2a35c6f572

found a couple

https://www.youtube.com/watch?v=x6VaUBx8SwY

https://www.youtube.com/watch?v=RvsjLukDDyg

 

[Teepee]

Aquaguards and Webtex inlines (both the same internals) froze for me.

Jared makes a good point with the UV and it would allow biological contaminants to be treated without boiling. Personally I rely on purification tablets if I can't boil but will probably and hopefully never have to use them.

 

[Twodogs]

There are other options to just boiling;

Rolling boil
Fast boil
Double boil
Extreme simmering

 

[Wayland]

For completeness do not forget chemical treatments although most require the water to be above 10°c of course.

I have always relied on clean snowball soup or bringing ice water up to the boil.

 

[rik_uk3]

Wayland have you done comparison boil time tests with snow v snowballs? I've only tried it with Welsh snow of course so it may be different with Arctic snow, but found compressing the snow into balls slowed the boil time down.

 

[carabao]

In Arctic, collect clean snow and boil, if really concerned puri tab. That's what we got taught and after two seasons on AMF had no problem.

 

[Wayland]

Didn't follow any scientific methodology Rik but snowballs seem to take slightly longer to melt yet contain much more snow.

End result about the same but far less time spent adding fresh snow with less danger of damaging the cooking pots as fresh snow soaks up the water causing hot spots.

I always start with a small amount of sacrificial water from my own supply to protect the pot then add a few snowballs at a time but never enough to lose sight of the water in the bottom.

Do that with fresh snow and the water soaks into the snow like a sponge and I've actually seen people burn through the bottom of an aluminium pot with snow still sitting in the top.

It's also easier to carry a pile of snowballs from a clean location away from camp to your fire/stove location than a handful of uncompressed snow in my experience.



.

 

[Alfreda]

There are a lot of benefits of water purification systems, A water filter will characteristically eliminate the contaminants in water such as mercury or lead and extra heavy metals by using ion conversation chromatography.

 

[Wayland]

Just found this picture to illustrate the point.

A good dense snowball behaves more like ice when it's melting which seems to be more efficient than soft snow.

By the way, unless you are at altitude, once you have reached boiling point the job is done, it really doesn't need a rolling boil if you are short of fuel.

 

[MikeLA]

interesting thread I have learnt something today Thank you.

 

[Ed Edwards]

I never really considered my water purification kit freezing... Some useful info here. I just use the Aquamira frontier Pro, so it can easily go on an inside pocket to keep it from getting freezing damage.

 

[Wayland]

Remember to keep it inside your sleeping bag as well then.

I'm usually keeping battery packs for my cameras in my clothing during the day but at night it doesn't really matter because the cold will not actually damage them, it just stops them working while they are cold.

For me the problem seems to be that you only need a water filter to freeze once and it's done for.

 

[Andy BB]

Yup - freezing filters is my biggest worry, particularly when its well below zero. Only need to make one mistake, and unless you're hot-tenting continuously, its all too easy for that to happen.