Welcome to Yosemite. Don't die.

[rlown]

strange.. I read those earlier today as well. You feel free not to filter. I'm gonna recommend filtering. Studies aren't always what they appear to be.

Phil, you even said you had it once. How is a filter that big of a deal?

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[robertseeburger]

Thanks to those who responded to my question.. I looked at all the links.. I will continue to treat water if I am at low elevation or on a major trail, and not worry about it if I am at an unnamed lake at 11,000 feet with no trail. My last trip, of 11 days, I treated water for 2 days and no treatment for 9. I realize there is a risk, but I think it is small from the information I have.. ( I realize that there are always critters above you!). I currently treat with pills as they are light.
I just find the streripen unreliable and the filters bulky and pain in ass. I would love to see this subject continue to evolve though with facts on actual cases in the high Sierra.

[maverick]

I just find the steripen unreliable

Why, have used it over a decade, in areas that I consider suspect, have never contracted Giardia. Big key is to wash hand thoroughly with soap and water, and don't share gorp (putting hands into the bag).

[robertseeburger]

On the steripen.. I have worked with two myself and one used by a backpacking partner. So 3 in total first hand experience. All of them got what I call the "dreaded red light". I asked what this was and was told batteries inadequate. The first time, it could have been operator error. the second time, I knew batteries were the right type and brand new. same thing happened to my partner with his. You get a red light telling you it didn't finish.
It has been two years since I last used it..so this is from memory. But I decided to switch back then.

[rlown]

was it because the battery was cold? I'd hate red lights as well.

[robertseeburger]

I had someone later tell me that the batteries might have been cold... but then...what good is that? I can't remember if it was morning only..when I got the red light.

[rlown]

It is about as useful as a frozen water filter.. Everything I bring that has batteries sleeps with me in the sleeping bag. Even the poly bottle of water sleeps with me. The water filter stays in the pack, but nestled in clothing so it doesn't freeze.

[maverick]

As Russ points out, if temps are cold, anything with batteries need to be insulated overnight from the cold, especially Lithium batteries.

[rlown]

And especially Alkaline batteries. Dropped two new ones into a camera once and it showed dead. Lithium are more forgiving, but still suffer from cold.

[Jimr]

My dad used to always tell me if the batteries are cold, hold them under your armpit for awhile. I always wondered why his battery powered stuff smelled, funny.