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Annual Check-up of Private Wells Recommended

PULLMAN, Wash. — Most people can take the safety of their drinking water for granted because their towns or municipalities monitor and treat it.

That’s not true for people whose source of drinking water is their privately owned wells. “People are inclined to believe their wells are safe to drink, but they shouldn’t make that assumption,” said Ron Hermanson, Washington State University Cooperative Extension agricultural engineer.

“There are some areas of groundwater contamination in many parts of the state,” Hermanson said. “Recent studies in the Columbia Plateau, for example, found that about 19 percent of 573 wells tested in the Central Columbia Plateau from 1942 to 1994 exceeded maximum contaminant levels for nitrate.”

Low concentration of pesticides were found in 67 percent of the groundwater samples collected from 49 wells in the Quincy and Pasco Basin in 1993 and 1994.

Hermanson recommends an annual well check-up to be sure your well water is safe to consume, more often if tests point to potential problems.

Once a year have samples tested for bacteriological and nitrate contamination. Most local health departments are equipped to conduct those tests and interpret the results, Hermanson said. Cost varies, but expect to pay in the neighborhood of $20 per test.

Any amount of nitrate nitrogen beyond 10 parts per million — the maximum contaminant level allowed in public water supplies — indicates human influence and should be monitored, Hermanson said. Animal and human waste as well as fertilizer can be the source of contamination.

Nitrate is linked to a fairly rare, but sometimes fatal disease of infants commonly known as Blue Baby Syndrome in which the oxygen carrying capacity of the blood is impaired.

“It’s not an adult hazard unless it’s quite high,” Hermanson said, “but if you find nitrate, you should test for pesticides as well. Nitrate dissolves in water and will travel in the ground anywhere that water goes.

“A portion of some pesticides ties up with soil organic matter. The remainder is free to move with the water and can leach down to the water table.”

Not all will make it to the water table, Hermanson pointed out. Some live in the soil-water system a long time. Many break down rapidly and pose no threat.

If you want to test your water for pesticides, you will have to send samples to a private lab.

“Testing for very many pesticides is costly,” Hermanson said. “The best thing to do is test for pesticides used in the vicinity. If you don’t know what is used, you can get a good idea by calling the county extension office.”

He says each county extension office in the state can also provide a list of certified private labs that can check for pesticides and bacteria. Most offices also have an extensive list of resources on water, water treatment and related subjects.

Hermanson said it’s also a good idea to test well water whenever you detect a change in taste, color or temperature.

A change of temperature may mean that surface water is contaminating your well. A color change may point to problems with your well casing. A change of taste could mean you have a dead mouse decomposing in your well.

If you don’t know the history of your well, you might want to test water samples seasonally to establish a benchmark against which to compare future tests.

What should you do if your tests point to problems? Water conditioning companies can offer a variety of solutions for most of them, Hermanson said.

“It’s a good idea to check with several water conditioning companies. Beware of fly-by-night operations that will sell you something and disappear.”

He said county health offices and the state health department as well as Cooperative Extension can help you sort through your options and steer you away from unscrupulous operators.

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