What to know about nitrates in well water

Published: May. 11, 2022 at 9:46 PM CDT
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EAU CLAIRE, Wis. (WEAU) -The Department of Natural Resources says one of the most common pollutants in Wisconsin well water is nitrate.

That can be caused by a number of things from fertilizer to human waste.

A retired hydrologist said he’s worried housing developments with well water are at a greater risk for this contamination.

A certain amount of nitrate is in water naturally.

When that level reaches 10 parts per million or 10 drops in every million drops, that’s when it could cause health concerns.

For more than 30 years, Neil Koch studied surface and ground water as a hydrologist.

Around eight years ago he began creating a map for Dunn County related to ground water and started to learn about septic systems.

“In my whole career, I did not deal with any septic systems,” Koch said. “I mostly spent time handling other contaminants and locating water for people.”

As he learned about them, he became concerned septic systems could pollute wells in places like housing developments.

The Wisconsin Department of Natural Resources said that’s sometimes been a problem where homes have their own well and septic system on lot sizes smaller than one acre.

“If you get 30,40, 50, 100 homes with half acre lots or less, and they all have their own septics, and they all have their own wells, it becomes very unlikely that everybody is going to be able to avoid everybody else’s septic effluent,” said Bruce Rheineck, a groundwater section chief with the DNR.

Rheineck said septic systems are designed to reduce bacteria and viruses making people sick.

When it comes to nitrates, Rheineck said: “The typical system installed in the state reduces nitrate content of the waste a little bit, but not a lot, so that’s where your setback distances start coming into to play for the nitrate contamination.”

State law impacts those setback distances.

It said how far a well can be from potential sources of contamination.

Making sure wells and septic systems are put in away from possible pollution is something the Eau Claire City-County Health Department does.

For existing wells, it also provides testing for things like nitrates.

“A lot of times we do see nitrate levels between 2 and 10, so not above a health level, but still above a level of what we would consider background levels of nitrate, and those are wells we really encourage owners to continue to test yearly to see if that nitrate level may be increasing, but on it’s own it doesn’t pose a long term health risk,” said Audrey Boerner, a public health specialist with the health department.

Boerner said higher nitrate levels could be caused by things like fertilizers, animal waster or a problem with a septic system.

The health department recommends getting your well water tested at least once a year for nitrate and bacteria.

For more information about getting your well water tested by the health department, click HERE.

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