Have your well water tested at least once a year.

What's down there? It could threaten your health.

RODALE NEWS, EMMAUS, PA—About 20 percent of the country’s population depends on private well water, but unlike municipal drinking sources that must regularly make sure their water is up to standards, with wells it’s up to the homeowner to test for potential contaminants. A report to be published in the June issue of the journal Pediatrics outlines the problem substances that can be found in private wells, including chemicals, bacteria, parasites, and viruses that can pose threats to infants and young children, and offers guidelines for testing.

THE DETAILS: The National Institute of Environmental Health Services (NIEHS), part of the National Institutes of Health, worked with the American Academy of Pediatrics (AAP) to draft new AAP policy to help protect well-water drinkers from illness caused by naturally occurring contaminants like radon and arsenic, chemical contaminants like pesticides and manmade fertilizers, and animal and human waste. While these aren’t healthy things for anyone to be drinking, “children are especially vulnerable to waterborne illnesses that may come from contaminated wells,” says Walter J. Rogan, MD, an epidemiologist at NIEHS and lead author on the policy statement and technical report.

WHAT IT MEANS: Well-water contaminants can be especially detrimental to developing babies and children. Nitrate, which comes from sewage or fertilizer, is the most commonly found contaminant, and the compound is particularly dangerous to infants younger than 3 months because they can’t metabolize it. Other contaminants, such as pesticides, have been shown to cause developmental problems and even cancer. Bacteria, parasites, and viruses can cause severe digestive distress, while natural contaminants found in the geology, such as arsenic and radon, can lead to lower immunity and cancer. The good news is that virtually any well-water problem can be treated. The best line of defense, though, is finding the problem and fixing it, if possible, so that filtration won’t be necessary.