Most of the time, the filter will be enough. But a belt and braces approach does not hurt.

Where are u from? or better, where are u going in this trip?

I go alot of places throughout the south, but my main hangout is Alabama. I have camped in several places though. Most of the streams in Alabama are quite clean I suppose. I've never had to filter the water nor have I gotten sick and I have drank face first from streams all from one end of the state to the other, literally. Although I agree there are many places that do need filtration. I do recommend filtering if you don't know the area and have no prior experience with the water in the area. I do take unnecesary risks sometimes, but I have never had a probem with it so far. I've had the Hershey squirts before and I can handle it. If I ever do have a problem, I know how to distill water using several different methods so I don't worry about it too much.

True enough, but I have read (don't remember where, possibly in this very forum) that viruses are quite uncommon in the USA. So, you could likely use a filter and be pretty certain of being just fine.