For those going to giardia prone areas, you should know that CDC studies show chlorine does not remove giardia. For that you need an iodine based tablet. Flocculation just cleans the water visually from debris and you need two containers, one to mix the water initially and a second plus a cloth to strain it into. Otherwise this tablet and similar ones are good for most water purification needs. There's a cheap method called SODIS which is free and uses solar energy. A clear bottle filled with water and placed in direct sunlight for at least 8 hours will purify the dirtiest water. It will still have debris but that is easily filtered out, and it doesn't leave a chlorine taste that many dislike.

Did you analyze the water or just making generalizations ("it certainly removes harmful bacterial, cysts, and protozoa.")

Yeah, thought so.

I have not had a chance to really use it. I bought it for an emergency, but I have no doubt it will work fine if military is using it. =)