Our goal at home or when traveling is to have germ-free water without chemicals or chlorine. Filtration is the best way to do this. I have discussed home filters. There are also filters designed for travel and camping. These are small units that have pumps so lake or river waters can be used. Since the recent outbreaks of giardiasis contracted by drinking the crystal clear, good-tasting mountain stream waters in our country, even wilderness packers need to carry some type of water purification. With the difficulty of boiling at higher altitudes and the distaste of chemical purification, filtration is the best way to go for backpacking, especially if large amounts of water are needed.
Most hand filters are granulated carbon, often with silver added. Though these are not ideal for home use, they are simplest for travel. They will take out some chemicals, but our biggest concern is microorganisms. Here the pore size of the filter, which should be clearly stated in the product information, is the crucial factor in determining what germs will be removed. The following chart shows micron sizes of relevant organisms.
| Organism
| Size in microns |
|
| Giardia lambia | 10–20 |
| Amoebas | 10–50 |
| Cryptosporidium | 2–5 |
| Campylobacter bacteria | .2–.3 |
| CMV and Herpes virus | .15–.2 |
| Retro virus (AIDS) | .1–.12 |
| Hepatitis viruses | .025–.04 |
The pore size of available filters ranges from 0.2–2.0 microns. They all will remove parasites, some will remove bacteria, but most will not take out viruses. In drinking water our biggest concerns are from parasites and bacteria; viruses, more unlikely to survive in water, are really a lesser concern. The Katadyn unit, claiming a pore size of .2 microns, may remove some viruses as well. It is the most expensive of the travel-pump units. Most of the available travel filters can clean about one to two pints per minute. If the water is dirty or turbid, use a prefilter such as a coffee filter or clean cotton bandana, for example, and pour the water through one of these before pumping. Prefiltering extends the life of the carbon filter.
Water Requirements
Water is essential for all life, and drinking the right amount is important to health. All the beverages we drink—teas, coffee, sodas, beer—are basically water that contains other ingredients as well. Drinking good water is still the best way, I believe, to obtain our fluid requirements.