Water treatment

"Yak dung?"

Joking aside, yak dung actually makes an excellent fuel.

In Nepal, the fresh yak dung patties are carefully aged in place, then picked up and placed against stone walls so that they will sun dry. When completely dry, they are used in space heaters, and the waste heat from that goes into the tea kettle.

When dry, there isn't much odor.

–B.G.–

Nick,
I don't think you always know when there is reason to suspect. When I used this approach, I got giardia twice, about a month the first time, but three years the second time because the symptoms and history didn't mesh with what the doctor was looking for. Pretty awful.

So I'm not willing to rely on my intuition or deductive powers. All water, unless boiled snow, gets pumped through a Sweetwater Walk-About, @10 oz. in a bag about the size of a pint bottle. That is one of the few concessions to weight that I'm willing to make. The second case of giardia ended with treatment in 2001. Nothing since.

Also note that with a pump filter, the potentially contaminated water does not get into or on any bottles or other gear. The only contamination that stays with me is on the inlet hose and prefilter, that are wrapped around the filter and kept separate from the outlet hose in the carry bag. Logically, some bacteria could migrate on the inside of the carry bag to the outlet hose, but this hasn't been a problem. So far, so good.

"If the hollow tubes are full of water but the rest of the filter is empty which you can do by shaking it out, and it freezes, the tubes will just stretch with no problem. When you backwash the filter, it stretches the tubes a little, including making the pores slightly bigger so any particles will be released and backflushed away."

Jerry please note that I said suck out the water, not shake it out. If you disconnect the filter from the bladder, and suck on the bite valve the water in the hollow tubes will be remove as well as the water outside of the tubes. Air would then occupy both sides of the filter. No stretching of the tubes would occur and the filter case would not crack.

"The hoses make it unwieldy. They weigh a little. You have to store them. One more thing to have to fiddle with. Not that big a deal though. A lot of people are happy.

Squeeze just screws onto water bag. Either gravity mode (although slow) or push on bag a little. Lighter. Simpler. Probably better for one or few people?"

Jan S. was referring to in line filtration, not gravity or squeeze. In the in line mode you suck on the bite valve of your bladder. Water then moves from the bladder, through the filter, straight into your mouth. Faster than gravity and no squeezing. You don't have to remove the filter from your pack and you don't have to fiddle with it. You can drink and filter while you hike.

"They weigh a little" All filters weigh something. chemical filters weigh the least, while UV pens, and pump filters weigh more. If you already own a bladder a, in line filter doesn't add that much more.

Steven

I didn't think you could suck the water out of the tubes. With the Squeeze, the tubes are hidden from view. If you sucked, would some tubes empty but others retain water? Can you apply enough pressure to suck the water out of the tubes? Or maybe it doesn't matter if there's water in the tubes?

If Sawyer could do some testing and identify a method to make it freeze proof that would be good. Maybe, for liability reasons they can't do that.

And many people are happy with in-line filters that require two lengths of hose. I've never used this, but it seems like having two hoses and hanging it from a tree is a little more complicated than just screwing the filter onto a bag. People should try both methods, if they want, and choose the one that works best for them. With two lengths of hose, the flow rate is higher so that's an advantage.

Re: Sawyer squeezes freezing and being damaged, i wonder if storing it in some higher percentage ethanol before and after use, would keep it from getting damaged?

I use the Steripen Opti with Aqua Mira for backup. I don't know your location (I assume you are in the US), but you can mail order the CR123 batteries and get them for a reasonable price. I get them from Battery Junction (I'm sure there's other decent online retailers too), and good name brand ones (which is what is recommended by the manufacturers of Steripen) are fairly cheap there. A 12 pack of Duracells can be had for around $32 including shipping. That's only a little over $2.50 per battery. Just something to think about since you termed them "strange batteries that are mostly unavialable".

Now if your comment has something to do with getting the batteries in the field (i.e. not carrying them in yourself), then I can't comment on that since I've never hiked there.

If you use Sawyer Filter connected to water bladder with "dirty" water.

Is there a device that you could be attached to water tube or in between. That has little UV lamp that lights up only when there is a flow in the tube.

For such a small volume of water you don't need big lamp and this could work with even CR2012 battery…

Just thoughts.

Any reverse osmosis UV lamps could fit?

http://reefbuilders.com/2013/03/11/microuv-inline-ultraviolet-sterilizer-cobalt-aquatics/

Maybe something like this? I couldn't tell what the power source was…

I am no that familiar with UV to know if that would be enough UV light to kill viruses. It's been a while since I took my microbio class.