[ghaff]

There are certainly clear, cold lakes in the Rockies. However, I really wouldn't advise just drinking out of them without filtering or other water treatment. Yeah, you'll probably be fine but there's definitely Giardia and Cryptosporidium in a lot of water sources that look perfectly clean.

[yaur]

http://ucdmc.ucdavis.edu/publish/news/newsroom/1789 is the only significant study that I'm aware of. My interpretation is that risks are substantially over stated for true "back country" sources in the Sierras and likely most other places where you would find drainage areas without significant human impact. I still filter water almost all of the time but I worry less when I can't for one reason or another.

[ghaff]

I don't really disagree. I expect that, as a practical matter, it's pretty safe to just drink water in a lot of remote places. That said, I also filter or use iodine even if I don't worry about medical facility cross-contamination procedures a lot of the time :-) It's not a lot of trouble and the consequences of getting an infection are unpleasant.

[hueving]

You'll need a citation for that. Otherwise it's just baseless speculation on par with saying you can drink from New Zealand lakes.

[ghaff]

To pick a random set of citations: http://tahoetowhitney.org/content/sierra-nevada-backpacker-w...

There seems to be a fair amount of disagreement.

Look. I have no idea personally. However, conventional wisdom is that it's prudent to treat water. If I were dehydrated and had no treatment options, I'd certainly take my chances and drink apparently clear, clean water. (And have on occasion.) But I wouldn't just set off on the assumption it wasn't necessary either.

[qume]

Have been drinking from NZ lakes and rivers for nearly 30 years and never had a problem. Did hear of a friend getting a bug about 15 years ago though.