The U.S Environmental Protection Agency (EPA) sets standards for approximately 90 contaminants in drinking water. Some of these contaminants are microbial. Many water suppliers add a disinfectant to drinking water to kill germs. Especially after a heavy rainstorm, your water system may add more disinfectant to assure that harmful organisms are killed. The microbes that are included on the EPA's list of contaminants are typically controlled by the disinfectant, chlorine. The EPA also sets standards for allowable levels of chlorine and its byproducts (trihalomethanes) in drinking water, as these too are associated with health risks. The EPA reports that people who drink water containing trihalomethanes in excess of their standards over many years may experience problems with liver, kidneys, or central nervous systems, and may have an increased risk of cancer.

Among the microbes that are controlled by chlorine are Fecal Coliform and E. coli, bacteria which indicates a contamination by human or animal wastes. Diarrhea, cramps, nausea or headaches may result from ingesting these microbes. Cryptosporidium is a parasite that thrives in sewage and animal wastes, sometimes finding its way to our water supply. This organism causes a mild gastrointestinal disease, cryptosporidiosis, which can be severe or fatal to people with a compromised immune system. Similarly, the parasite, Giardia lamblia , originates in sewage and animal wastes, causing gastrointestinal illness when consumed in drinking water. A complete list of contaminants along with the maximum levels allowed by the EPA can be found at their website, http://www.epa.gov/safewater/c ontaminants/index.html.

Happily, modern water treatment systems supply the safest drinking water in the history of civilization. Whether your water was treated by a public or private supplier, it must meet the EPA's drinking water standards to protect public health. Still, some people have concerns about the byproducts of chlorine. These are the compounds that result when chlorine reacts to naturally occurring elements in water. They are collectively known as trihalomethanes (THMs) and excessive amounts of these over time are associated with health problems. If your water supplier uses chlorine, and you have concerns, a carbon-based filter on your faucet is quite effective at removing THMs and other toxins. According to the site WaterFilterRankings.com, the filters that best remove chlorine and chlorine byproducts are from Paragon, Aquasana, Kenmore, GE and Seagul. Another solution is to leave tap water uncovered in the refrigerator for 24 hours. The chlorine and related compounds will naturally make their way out of the tap water.

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