I have a Hiker Pro filter, which has worked very well, but the basic procedure that I use the most is boiling. It is thorough, simple, and uses equipment that I almost always have with me. The only disadvantage is that sometimes I must carry additional fuel.

Believe me, I have sanitized some truly awful water by boiling. For some reason, boiling does not seem to be discussed in the section cited above. This is a very surprising omission.