Water Treatment

At a usage rate of 2 gallons per person per day (enough for cooking, drinking, and dishes), a 55 gallon drum of pure water will last a family of 4 almost one week. I say this to point out the fact that there is no way possible to store all of the water you will need for a long term emergency. For this reason, a means of purifying enough water for a family needs to be something that's on everyone's radar. There are basically two methods of purifying water: chemical purification and mechanical purification.

Chemical purification: This involves the addition of a chemical substance to the treatable water that will kill all of the bad bugs without harming the person drinking the water. Common chemical additives include Iodine, in crystal form or as a tincture, and Chlorine, often supplied by a bleach solution (but not the bleach that smells like flowers) or granulated sodium hypochlorite, like the pool shock you buy at the pool supply store.

Mechanical purification: This consists of running the water through a filter that strains out the solid particles, exactly like the sieve that you use when making macaroni and cheese. These are broken into three categories based on effectiveness at removing bad things. The first classification is filter, and it removes 98% of bad stuff and has a pore size of about 4-6 microns. A microfilter removes 99.9% of bad stuff, and has a pore size ranging from 1-4 microns. A mechanical water purifier removes 99.99999% of bad stuff and has an effective pore size of less than 1 micron. The two types of mechanical filters are pump filters that require an energy input and gravity fed filters, which rely on gravity to force water through the filter element.

Use of chemical purification means requires some knowledge of chemistry and relatively precise measuring techniques, and even then there is no protection from heavy metal contamination. For this reason, I think that mechanical filters with activated carbon after filters (to remove the heavy metals) available for it are the best way to go.

For the purpose of making fairly large amounts of potable water with minimal maintenance, Rand and I have pretty well settled on using the British-Berkey filtration units. They represent a significant initial investment, but are reputed to be more or less trouble free and over the life of the initial filter elements (which are replaceable) the cost per gallon of water comes out to just under 4 cents, and forever after that the cost per gallon of water falls to around 1.7 cents.

Another good option for making smaller amounts of water (more appropriate for short term emergencies or backpacking) is the katadyn pocket filter. It breaks down to 1.7 cents per gallon initially and 1.1 cents per gallon after that. Food for thought.