If you get your household water from a private well, you probably know that you should check the well annually for potential impurities like Giardia intestinalis, Shigella spp., E. coli 0157:H7 and coliform bacteria, Campylobacter jejuni, nitrate from sewage or fertilizer, radon, and arsenic. Groups like the National Ground Water Association, NSF International, and the Centers for Disease Control and Prevention advocate for an annual assessment of water for the 15 to 20 percent of U.S. households that rely on wells.

But if you have infants or young children at home, you should be aware of a new policy statement issued by the American Academy of Pediatrics. Since infants in particular cannot metabolize nitrate, the AAP recommends that you not use water with a nitrate concentration of more than 10 milligrams per liter to prepare infant formula or give well water to a child younger than one year old. The statement suggests using bottled water for infants when nitrate contamination is detected or when the source of drinking water is unknown.

The National Institute of Environmental Health Sciences (NIEHS), which worked with the AAP on its recommendations involving children's safety, goes further in its own warnings. If you think your well has suffered structural damage, you're at risk of drinking tainted water and should have the water tested in case contamination occurred, says the NIEHS. The illustration (above) shows the suggested distances between a well and a number of possible sources of contamination; the U.S. Environmental Protection Agency says that farther is better.

Private wells aren't subject to federal regulations and are only minimally regulated by states, according to the NIEHS. Because potential water problems differ by region, pay particular attention to alerts from state and local health experts.—Ed Perratore | e-mail | Twitter | Forums | Facebook

Essential information: Call the EPA's Safe Drinking Water Hotline (800-426-4791) to see whether your municipality provides free or inexpensive testing or to find a certified testing lab in your area. And read our review of various types of water filters (ratings available to subscribers) and learn how to decipher your water report.