COLUMBIA, Mo.– If you use well water for cooking and drinking, you should regularly test the water for contamination, says a University of Missouri Extension water quality specialist.

“Bacteria is one of those things that is easy to control, but it is something you need to check for,” says Bob Broz. “The best time to test a well for bacteria is in late spring or early summer during wet weather.”

According to the U.S. Centers for Disease Control and Prevention, 52 percent of Missouri wells had high levels of bacteria.

Broz says wells should be tested at least once a year for bacteria and nitrates.

“There presently is no law that says you can’t use the water,” he says. “But if it does test positive for bacteria you should shock chlorinate it to get rid of the bacteria in the system.”

Broz says shock chlorination is a fairly simple application that anyone can do.

The absence of bacteria does not guarantee water is safe. As water moves through the ground and rock, it dissolves many different minerals. Many, like calcium and magnesium, aren’t harmful, but others, such as arsenic, are health risks.

Broz says another component is wellhead protection.

“Look around the pipe that indicates where the well is and see if any close activities could possibly cause water contamination,” Broz says. “Things such as pesticide or fertilizer storage and handling, on-site sewage systems, or even surface water surrounding the wellhead can be contaminants.”

Water testing can be expensive and laboratories only test for contaminants that are specifically requested. So it is important to determine possible contaminants and then decide what to test for.

“Water is a very precious resource and we don’t have a lot of it,” Broz says. “Groundwater is all connected, so something that is going on 3 miles down the road from you is affecting the way your well is operating. So understanding how water moves under the surface and where water is coming from is all very important for the private owner to recognize.”