Grapefruit Seed Extract

i used this during my mountains to sea through hike in NC. Recommended by a friend who uses it in third world countries to purify her drinking water.

6-8 drops per liter and only a slight bitterness.

Let sit for 30 min.

Not reviewed by the FDA but Im confident in its effectiveness.

Also great for your gums and teeth when added to toothpaste while on the trail as well as a host of other health benefits.

Extensive research has been done, check it out

...in fairness, I haven't tried this. Nor would I. If there is a credible body of evidence supporting leon's description, I would defer to that, but the consequences of not purifying your water properly can be quite serious and I would not suggest experimenting. Even if you know someone who has used this and not gotten sick, remember that it may just be that they didn't drink contaminated water!

http://www.terressentials.com/truthaboutgse.html