North Mankato alleviates contaminant reading in water

Tim Krohn, The Free Press, Mankato, Minn.
·2 min read

Jul. 2—NORTH MANKATO — North Mankato's drinking water had one contaminant that tested above federal standards last year, but the city said the high reading was an anomaly and recent tests show the contaminant well below the federal acceptable levels.

The Environmental Protection Agency limit on trihalomethanes, or TTHMs, is 80 parts per billion. North Mankato had one a test that showed more than 119 parts per billion.

Trihalomethanes are the result of a reaction between the chlorine used for disinfecting tap water and natural organic matter in the water.

Water Supt. Duane Rader said recent tests in upper and lower North Mankato show the TTHM levels are now well below the federal levels.

"We have that under control now."

He said levels have always been low in past years, but one sample was taken in a building in upper North Mankato last year that showed a high level of TTHMs.

Rader said that the sample was taken in a building where there was temporarily low water use so water flow was very low, likely leading to the higher levels of TTHMs.

He said the city has been making sure higher levels of water are flowing through the pipes more often.

In the past, the state had only required the city test for TTHMs once a year. But because of that high reading, the city must now test four times a year. Rader said they've done two tests this year and that if the low levels continue throughout the year the state will allow the city to go back to annual testing for TTHMs.

"The state dictates how many tests we do and how often. And once a year the state comes down and tests for a variety of things," Rader said.

When people consume TTHMs at high levels over many years, they increase their risk of developing bladder cancer and other adverse health effects.

The city recently posted its annual Drinking Water Report based on tests taken last year:

(northmankato.com/sites/default/files/pdfs/2021%20Consumer%20Confidence%20Report.pdf)

Tests showed other contaminants in the city's drinking water were well below federal standard levels, including lead, nitrates, barium, mercury, radium, acids and copper.

The U.S. Environmental Protection Agency sets safe drinking water standards that set limits on the amounts of specific contaminants allowed in drinking water.

The U.S. Food and Drug Administration regulates the amount of certain contaminants in bottled water. Bottled water must provide the same public health protection as public tap water.

Drinking water, including bottled water, may reasonably be expected to contain at least small amounts of some contaminants. The presence of contaminants does not necessarily indicate that water poses a health risk.

More information about contaminants and potential health effects can be obtained by calling the Environmental Protection Agency's Safe Drinking Water Hotline at 1-800-426-4791.