Though much of the information in this thread is correct, there is some advice here that could be expanded upon or changed (how is that for keeping peace in the house).
By-the-way, my backpacking partner (mentioned in my previous post), who was contaminated with Giardia, is an emergency room physician. He would be the first one to tell you that if he hadn't been hooked up to an interveneous drip in the hospital for hydration, he would not have survived his ordeal. Throughout history, we have records of countless outdoors men and women who fell victim to naturally contaminated water...contrary to Hollywood movies and survival t.v. shows. Dysentery and dehydration, caused by contaminated water, can kill you. I (we) have been to several underdeveloped countries and have watched this happen with our own eyes. My mother, who was a medical biologist (as in, doctor mom), seen several people die of dehydration in our own U.S. hospitals from exposure to contaminated water. Folks need to understand *why* and *how* contaminated water effects the human body. Only then will they make clean water a priority in their outdoor travels.
Boiling in general DOES NOT address harmful chemicals in the water. When I was involved in a government water quality study (for fisheries) on one of our largest rivers in the U.S., we found very high levels of fertilizers, pesticides, measurable radiation from a nuclear plant (100-miles up river), and naturally occurring radiation from our atmosphere. No, given the levels of fertilizers and pesticides in the water, your water filter, boiling, chlorine, bleach, iodine, etc., would not make some of this water we tested (50-miles from any city) safe for drinking. That is not to say that Bob with the iron stomach couldn't drink it and live. Myself, I can look at dirty water and get sick. Though, I have ingested my share of untreated swamp and jungle water in Vietnam, Thailand, and Panama without any issues (some of my mates weren't so lucky).
Before heading to the outdoors with the intention of treating your own water found along the way, do some serious study (get some books and advice from experts) on the water treatment options, and some study on the area in which you will be going into (this might change your treatment options). The idea is to come out of your adventure healthy and well. In the primitive survival courses and basic survival courses that I have taught in the local college, and in private, we spend a couple of days just on water treatment options and how best to perform these methods. We have seen a number of people contaminate their water bottles while in the process of using a water filter. Safety will be found in the attention to detail with all of the treatment options.
