filtering water in cold temps

I have never had success filtering water much below zero. It can work but the filter will freeze up if you leave it out too long. It will have to be stored with you inside your jacket or sleeping bag at all times. If the filter freezes it can damage the filter. Once it freezes you will be unable to use it the rest of the trip.
If you are expecting cold temps only at night but above zero during the day it will probably be fine as long as you keep the filter warm at night.

When I'm camping in winter, I bring a 1.5L Nalgene bottle.

While hiking, I eat fresh snow and drink water. Even down to -10º, I can safely eat a lot of snow without cooling down to a dangerous level because of the amount of exertion I'm putting out just walking around.

When I'm in camp, I fill my Nalgene with either stream water or snow, and I boil it. Boiling the water lets you have a nice, warm Nalgene to bring into your sleeping bag with you. By morning, you have 1.5 liters of clean water to drink all day.

So, no filter used in winter. If you're gonna filter, though, I would try the Sawyer and just keep your jacket ready to put the filter under while it does its job. Keep it in your coat pocket the entire trip to prevent freezing.

Dale, for the issues you mentioned, I switched to a Steripen Opti. I made the switch after trying to filter water along the ice covered rocks of lake superior one night.

I use a coarse prefilter to get rid of floaties, and then zap the water.

It's not a foolproof system, but more so than a traditional filter.

“ If I keep the filter close to my body when not in use, will it be warm enough to not compromise the integrity of the filter and will it still perform well when filtering?”

That’s hard to predict. I used the First Need Filter in the Midwest below freezing. I thought I kept the filter warm. However, when I got home and did the ‘broken filter’ test, it failed. And I broke 2 filter cartridges this way. So I just never take the filter out in below freezing weather.

Now I just melt snow with my alcy stove. And for drinking, I don’t bring it anywhere near a boil (i.e., cold; 50-90F); and that saves a lot of fuel. But I do whip out my steripen opti to sterilize.

Good luck with winter water.
-Barry
-The mountains were made for Tevas

Could you elaborate on the 'broken filter' test?

I didn't even think about a steripen. Don't these run on batteries? The only time I've ever been camping in single digit temps, our devices that ran on batteries stopped working. Then again, I didn't have them close to my body. I'm assuming that the steripen in the jacket should work okay….

“Could you elaborate on the 'broken filter' test?”
Hello Travis,

Yea, I didn’t know what to call it.
You take 1qt of water, put about 4 drops of blue dye in it; the water becomes very blue. Filter this and it should come out perfectly clear. If you see any hint of blue, then the filter is compromised.

This is First Needs test and it won’t work with any other filter; not even ceramic filters. They all let blue water through. In fact, that’s one of the reasons I bought a First Need. For muddy, stagnant, tannic lakes (typical in the Midwest), all filters let the darkness go through while the First Need turned the water crystal clear. Now the other filters (like a Hiker Pro or Vario for instance) probably still filtered OK, but psychologically, I had a hard time drinking brown water.

I’ve even filtered grape soda and root beer with the First Need and those drinks came out crystal clear! However, the result tasted like corn syrup.

I haven’t used the filter that much since I moved out to the Rockies. The mountain water is clear to begin with :).

-Barry
p.s. I enjoyed hiking your Kettle Moraine South Trail when I was there a few years ago.

There is another test that can be performed though I will have to look it up. It involves back flushing and bubbles. I think that Platypus told me about it and I'm assuming it will work with the Sawyer too since they are made of the same thing (I think). I will look it up or call the folks at Platypus.

We use a Steripen Opti as well, at all temperatures.
Batteries: use brand-name lithiums and keep them warm. Anything above 0 C is fine.
Don't try using non-lithiums or cheap lithiums – they can't provide the current.

Cheers

"I fill my Nalgene with either stream water or snow, and I boil it."

Max, I'm sure you don't boil the water and snow in a plastic bottle. Is it not easier to put the snow right into the pot? (plus the small amound of water needed)

I was wondering about this also.

I'd still like to understand the advantage in putting a platy or nalgene in the shoe vs. pouring HOT water over them in the mornings.

I have come to just use chemicals in below freezing temps and my sawyer squeeze the rest of the time. I don't want to chance a frozen filter, and as far as I know, there is no real way to test them. But, I can be sure that it is not frozen if the temps aren't below freezing. The chemicals do take a tad longer to work in colder temps, so I generally give it at least 10 – 15 minutes longer, depending on turbidity of the water. However, I rarely find myself waiting on water to be treated with chemicals… I have been pretty lucky to be able to have enough on hand while the other is treating. That is the nice thing about hiking in areas that have fairly good water sources along the way…

I use a pot to melt the snow, then pour it into my Nalgene. When I camp in the winter, it's with friends that have alcohol stoves and we bring a pretty decent sized pot (still pretty UL, all things considered).