Please do not use iodine! The EPA says it's for emergency use only. Iodine really did a number on me when I tried using it to disinfect water back in the 1980's. I developed a horrible overall rash with deep lesions that left permanent scars. To this day I cannot eat anything with iodine in it, including iodized salt and any seafood.

Chlorine bleach decays into nasty carcinogens like dioxin, so you don't want to use that either.

For chemical disinfection, try chlorine dioxide. It's used in many municipal water systems and is probably the safest. AquaMira is available in both liquid and tablet form, and Katadyn sells it in tablet form. Its problem is that it takes a long time (up to several hours) to kill protozoa like giardia, but it will zap bacteria and viruses in minutes.

The Sawyer filters don't contain charcoal so won't filter out the chemical taste.

However, as ETSU Pride says, check to see if you even need to worry about viruses in the locations where you hike. I would only worry if I were downstream of inhabited areas.

In addition, most of us have been vaccinated against the deadly water-borne viruses, like polio and hepatitis A. Of course there is norovirus, but that won't kill you, just make you wish it would!