On Drinking Water … it’s NOT the water.
The bottom line on filtering, etc. is this: a lot of filters have been sold in the past 25 years supposing it to be the water, and all water, even in the most extreme places, since hikers were getting sick even in extreme places. It didn't make sense to me - but I bought filters anyway - since some of our deer hunting is done in the quasi-desert along with the cows and other creatures that drink, bath, and wallow in the few streams. So, yes, there we filter. And so I also have thus filtered most of my water even in the high country, since I now have the filters. But it still didn't make sense - since some of the water we drink in the high country is basically immediate snowmelt or filtered by the ground, or both. And I have also drunk some pretty nasty un-filtered stuff - and have done fine. Then we went into Unit 26 on a guided hunt - and drank unfiltered water there - along with the pack animals, deer, bighorn sheep, whatever, and didn't get sick. If any water `should have' been filtered, by theory, it should have been that water. But we did fine. Some time after that I talked with a hunter in 26, same area, same specific area within 26 … almost exactly, who got so sick he had to pull out. But we did fine. (Redundancy intended.) Filtering wasn't even an item of concern for the outfitter and guide (and they do this for a living – and, in addition, probably don’t want sick clients). And note: we camped directly downstream of an area thick with Bighorn Sheep (see species in article below).
Then I happened onto a blurb about a study done in the Sierra Nevadas. And with purpose I name Sierra Nevadas, because to those of out west – we would probably assume the Sierras to be the most contaminated or our wilderness environments. Someone really tried to get to the bottom of water quality in the mountains - and found that even the most contaminated water in the Sierra Nevadas was WAY cleaner than the treated L.A. drinking water. So why do L.A. hikers get sick in the Sierra Nevadas and not get sick drinking L.A. water????
It's not the water.
Here's the situation: hiker A, your dear friend, goes behind a rock or bush to relieve him/herself. Now happy he/she comes back into camp and finds out he/she has the task of cooking dinner that evening. He/she cheerily steps up to the task … after all, it is his/her turn. Sabe? Need I say more? It's not the water - it's hygiene. What changed in the early 80s was not the water - but perhaps a dramatic drop in outdoor hygiene. And so a lot of water filters were sold. Instead, what should have been `taught’ were hygiene and manners, and common sense. And if anything was to be sold, it would be soap.
Not long after reading the article I took a wilderness first aid course - and after one of the sessions talked about it (the study) with the instructor. He said that the article that I referred to (link below) is now required reading for their wilderness course. (As an instructor of fledgling outdoor enthusiasts, he got tired of getting sick taking these people out on trips where they took turns with cooking and dishes duties.)
So, what should you do? Filters are relatively cheap – no reason not to get one and use it - but also think hygiene. Wait! … don’t just think hygiene … DO hygiene. Use soap; use an antibacterial soap, waterless antibacterial soap, if necessary. (Waterless antibacterial soap is also good for the glove box on road trips.) If you are with questionable people – do your own cooking. In the great outdoors, on your once-in-a-lifetime hunt, don’t be lazy or stupid and not concerned with the important things.