Sierrafan wrote:
> I drink out of the Merced all the time (upstream of the
> campgrounds)...the water tastes great, icy cold, and have never
> had an issue.
>
> Bob Rockwell's article that was linked by Rob is an
> enlightening one; after reading it some time ago, and doing
> some more investigation, I realized that we've likely been fed
> a bunch of baloney all these years. One of the interesting
> stats is that San Francisco's water supply, deemed pure enough
> for no treatment, has more giardia than Yosemite's rivers, in
> general. So I carry a stainless cup with a carrabiner for a
> handle clipped to my pack or belt, and dip away, nothing
> simpler.
I've heard this before, but San Francisco's water supply is treated with chloramine. I don't know if they need the basic filtration, aeration, chlorine dioxide, etc that most water supplies go through, but they do at least put something minimal in it to kill the nasties like bacteria. Or it could just be for some mild effect with microorganisms that get picked up along the system.
http://sfwater.org/mto_main.cfm/MC_ID/13/MSC_ID/166/MTO_ID/399I've read that some on SF worry because chloramine doesn't take care of cryptosporidium, which other municipal water supplies eliminate with micron filtration and chlorine dioxide. My water supplier goes through a whole bunch of steps, and my new house is just a few blocks from one of their treatment plants. It's surrounded with barbed wire fence and lots of trees.
http://www.ebmud.com/water_&_environment/water_quality/water_treatment_plants/default.htm> Again, borrowing from Bob Rockwell's thoughts, "drink smart" is
> the key; running water that looks clean, and you know there's
> not a cattle ranch upstream might be considered safe, where a
> foamy trailside trickle from unknown origin with a dead cow
> just over the bluff would probably best be avoided or at least
> treated well...8^)
I was considering going to Isle Royale NP backpacking. They absolutely recommend filtering or boiling because the moose tend to unload their wares, which include several assorted parasites.