Ideally you want both, Jackie.

Even if you chemically treat water you still have things in them that won't make you stick, but will make for an uncomfortable drinking process. Sediment, mostly. I'd chemically treat and then drink it through a filter straw similar to what many bottle companies are selling. Charcoal based filters meant to filter out chlorine and other particulate matter.

Water down here is so full of various things that it would plug up any filter straw rather quickly. And because of that I am not entirely confident chemical treatment would be good enough for my standards. I would probably just filter the water through a bandana or piece of t-shirt and then boil it as well as chemically treat it. I've tasted boiled river and pond water and it taste like crap.....so having some chemical flavor in there is a step up.

Although I wouldn't be surprised if after years of growing up swimming in the St. Johns, Wildcat Lake and numerous Spring fed runs and creeks that I am immune to what's in the local water. Lord knows I've swallowed enough on accident. But I'm not about to put that to the test.