What Makes Well Water Safe to Drink?

Most well water is safe to drink, but there can be health risks associated with well water used for drinking. Well water may contain microorganisms and chemicals that could make you sick. "Unlike public drinking water systems that serve many people, public health authorities don't check the quality of well water," says Michael Gochfeld, M.D., Ph.D., a professor of environmental and occupational medicine at the Robert Wood Johnson Medical School in Piscataway, New Jersey. That means it's up to the well owner to ensure that well water is safe to drink.

About 15 percent of Americans rely on well water for drinking, according to the Environmental Protection Agency (EPA). Contaminated well water can cause nausea, diarrhea and vomiting and potentially lead to serious health problems, such as cancer, kidney disorders and brain damage, says Dr. Gochfeld. Contaminants known as nitrates are especially hazardous for infants because they can disrupt oxygen flow in the blood of babies, according to the EPA. Regular testing for contaminants along with other precautions will help ensure that well water is safe to drink.

The EPA says that well water should be tested every year for bacteria and nitrates. Shallow wells are most at risk for bacteria leading to diarrhea and vomiting, according to the EPA. Wells near septic systems and livestock are susceptible to nitrates because they derive from human and animal waste. As of 2010, private labs charge $10 to $20 to test for these contaminants, but your local health department may test for free, according to the EPA. For wells used year-round, the best time to test is late summer. For camps and summer homes, the EPA recommends testing when you move in.

Well owners should test every three to five years for lead, arsenic, radon, uranium and certain other heavy metals, according to Gochfeld. The EPA suggests also testing for these contaminants before using the well for the first time. These tests may cost from several hundred to several thousand dollars, according to the EPA. If a contaminant is found, the results will include the concentration of the contaminant and whether this concentration exceeds the safe drinking water standard.

The EPA recommends that wells be 50 feet away from septic tanks and livestock yards, 100 feet from petroleum tanks and liquid-tight manure storage and 250 feet from manure stacks. Your well should also be located so that rainwater flows away from it. Rain water can pick up harmful bacteria and chemicals on the land's surface. If it pools near your well, it could seep in.

Proper maintenance of your well will help keep your drinking water safe. The EPA recommends regularly inspecting your well for cracked or corroded well casings, a broken or missing well cap, and settling and cracking of surface seals. Periodically check any underground storage tanks that hold home-heating oil, diesel or gasoline for leaks. Make sure your well is well protected from the wastes of pets, wildlife and farm animals. Minimize use of fertilizers and pesticides, which can leach into ground water.

Filters and other private purification systems can help remove contaminants in well water. Those that use carbon filters remove lead and some heavy metals. Others, such as reverse-osmosis systems, strip out contaminants not necessarily caught by carbon filters. "Water filters may give you some peace of mind, but you still need to test because filters won't remove all contaminants from well water," emphasizes Gochfeld.