There's probably a macro level filter (dirt and maybe silt) sitting in front of the pump. (Something like that would not filter microbial pests, which I assume is your concern.) I hope the water is filtered or treated in some way.
The real thing to worry about is giardia parasites, spread by feces contamination uphill (human or wildlife). It's the reason I wouldn't drink wanter in the backcountry unless it's directly from high snowpack.
> It's the reason I wouldn't drink wanter in the backcountry unless it's directly from high snowpack.
If you are at a certain elevation, and it is known that there are no villages above you or mining going on, any flow coming down the slopes is likely safe to drink, regardless of whether you know for sure that it comes from a snowpack. It has been argued that filtering water in the backcountry is often unnecessary, in spite of what companies like MSR suggest with their marketing.[0] Certainly, if you visit mountain ranges like the Carpathians, the Chilean side of the Andes, or the Pamirs, you can see that travelers and locals alike fill their bottles from the waterfalls without incident.
Yeah, that's what I've read. I was mostly handling water in well-travelled wilderness in the Appalachians and Rockies, though. And from what I understand there's enough of a disease load in say, the deer population in the Sierras, that you might not want to be doing it even if you don't think there's humans upstream. shrug Wasn't a huge amount of trouble, my brother has a pretty high-end pump filter.
> Is boiling water an effective safety precaution?
For giardia and most other disease-causing microorganisms, yes. Boiling (for a few minutes) is enough to kill them. But it doesn't fix everything (e.g., heavy metal contamination, botulism spores).
Has a healthy adult ever been harmed by ingesting botulism spores? You're not supposed to feed honey to babies less than 12 months old because it can contain botulism spores, but for people older than that honey is considered safe. See http://edis.ifas.ufl.edu/aa142
Sure, and there is a pretty low background rate of botulism anyway. But I don't want to say "this is a completely safe way to make water potable" when I know some additional corner cases apply.
