How to Test Water Purity
Many people are concerned with the presence of impurities in their water that could cause illness or disease. Examples of these contaminants include bacteria, nitrates and metals. These are all easily detected using at-home test kits. Tests that state they meet U.S. EPA standards use officially approved methods, similar to those used in an environmental laboratory.
First: Bacteria
The presence of certain bacteria is an indicator that the water system is contaminated by human or animal waste and therefore could also carry disease-causing bacteria and viruses (pathogens). These pathogens can cause mild diarrhea or worse illnesses, such as hepatitis. Test kits are readily available for several different bacterial indicators: coliforms, E. coli and enterococcus. Any of these tests are acceptable. They usually involve adding a sample of water to a bottle containing a solution that encourages bacterial growth. The sample then requires an incubation period, necessary to let any bacteria present grow until it is detectable. Bacteria presence or absence is determined based on the color that the sample turns during this incubation period; the color varies according to the test.
Second: Nitrates
Nitrates are not a concern for most people, but are a serious consideration for pregnant women or children. High levels cause "blue baby syndrome" and this is very serious. The easiest way to detect nitrates is with test strips that are simply dipped into the water sample. The color that develops is compared to a color chart provided with the kit, which in turn gives the concentration of nitrates in the water.
Third: Lead
The metal that causes the most concern is lead, particularly in homes with older plumbing. Even low levels can cause developmental problems in small children. Lead and other metals are detected using test strips similar to those described for nitrates.