You can make water suitable for drinking by using thermal, chemical or filtration techniques. Depending on the water quality, sometimes it takes a combination of the three to really do the job right.
Bring the water to a rolling boil and keep it there for 1 minute at sea level and 1 additional minute for every 1000 feet of elevation above sea level. If you don’t know your elevation, boil for 10 minutes. This method will kill parasites, bacteria and viruses, but won’t eliminate chemical or heavy metal toxicity.
The whole idea behind chemical treatment of drinking water is to poison all the critters that are swimming in your drink. Iodine and chlorine are the old standbys. Make no mistake about it, chemical water treatments are toxic, at least to the organisms being treated. The key to safe use of these products for human consumption is to carefully follow manufacturer recommendations. Additional caution must be exercised because some people have chemical sensitivities or are allergic to some of these substances (particularly iodine).
The effectiveness of a chemical purifier depends on 5 factors — product freshness, water temperature, water clarity, exposure time, and dosage. Check the expiration date on the product package to make sure the chemicals are fresh. For more effective purification, raise the water temperature to 60 degrees F or above. Pre-filter or let the water stand overnight to allow sediments to settle, and then treat only the clear water. Allow the recommended treatment time, and use the full dose of chemical.
For using liquid chlorine to disinfect drinking water, add 1⁄8 teaspoon (or 8 drops) of regular, unscented, liquid household bleach for each gallon of water, stir it well and let it stand for 30 minutes before you use it.
The recommended dosage for liquid iodine is 5 drops of 2% tincture of iodine in a quart of clear water. If the water is cloudy or especially cold, increase the dosage to 10 drops. Shake the container to disperse the iodine and then let it stand for half an hour before drinking.
Among the good filters are two types worthy of consideration — a membrane filter and a depth-type filter. A membrane filter utilizes a porous membrane that permits water to pass through, but stops particulates larger than the size of the pores. These filters clog quickly but are easy to clean.
A depth-type filter utilizes an element such as a ceramic block that is porous enough to allow water to be forced through, yet dense enough to capture the bad stuff. Care needs to be exercised with this type of filter element, to prevent accidental breakage. Clean the element by scrubbing or back-flushing when clogged.
If a carbon element is included, the system will be able to remove some chemicals and heavy metals, as well as improve the flavor and smell of the water.