Water treatment below zero

[Piiber Teravhammas]

As the winter is comming I have a question about lightweight solution for water treatment. I have never used any deivce nor chemical before as it has not been an issue. I have not had any issues carrying drinking water for 2-3 day trips, more often it is possible to visit a store or a spring is on the way.
Also I have just boiled water when I have ran out.

Now straight to topic. Filters are prone to catastrophic failure below zero. I would trust to use on if the day temperatures are on the plus side and it gets below zero only during the night. However, when the 24h mean is below zero, I would not trust the "keep near body" method to avoid filter freezing.

Tablets? Any tablets that leave no nasty taste?

Etc...

 

[edh]

These are OK, or other silver-based variants

 

[Teepee]

I don't find any of the common treatment tablets any nastier tasting than our domestic water supply, it's packed with Chlorine and if I open a bottle of tap water from home on a hillside, I can smell it.
I use normal Aquamira drops when needed, or strips of Aquatabs that are always in my FAK.

Treating or filtering water in sustained sub zero temps is a game I won't play again I can avoid it. Tabs/liquid take much longer to work in the cold, and will fail to work on any contaminants locked inside ice crystals. Even pre-fiiltering to remove turbidity is a pain.
Practically, when the temps are low enough to risk my filter freezing for a substantial part of the trip, it doen't get packed and water is always then boiled to treat. This takes more fuel, but means your not carrying water for 1-2 hours, going thirsty waiting for the treatments to work, or going without a regular hot drink in the cold.


FWIW, I haven't treated water for 2 years now in winter...the last time a suprise hard frost came at night and froze my Sawyer near the end of a trip with low amounts of fuel left.

 

[Whiteburn]

As @Teepee states the chemical treatment of drinking water at temperatures below 10C takes a LOT longer & at close to 0C unreliable. If going this route I'd be looking to pack an insulated 1L Nalgene, warm the water to ~20C then pop it into the Nalgene with the tabs or drops.
I haven't any experience but UV treatment may be a more reliable option but not UL.

 

[Piiber Teravhammas]

When there is snow, then it is easy enough to melt it. There have been occasions when everything is frozen solid (lakes and rivers too) and no snow. I think I really have to look into making the "peg extractor-ice chip" tool. I have titanium ready

 

[Teepee]

The dirtiest snow I've ever melted was in Estonia.

Weeks old snow.... full of bird droppings, leaves, dust, bear fur etc. It blocked the cotton filter endless times on the way through and froze on the exit.

Boil and let it sink/float, then tuck into some random shelf pickings from Rimi, and then a bottle of Vana Tallinn worked quite well.