West Des Moines cuts ‘forever chemicals’ from drinking water
At least three cities have shut down wells contaminated by PFAS. (Photo courtesy of the Arizona Water Science Center)
The treated drinking water of West Des Moines no longer has detectable amounts of two prominent toxic chemicals that persist indefinitely in the environment, according to recent test results.
West Des Moines Water Works shut down a contaminated well late last year after sampling by the Iowa Department of Natural Resources revealed it had troubling levels of perfluoroalkyl and polyfluoroalkyl substances — commonly referred to as PFAS, or “forever chemicals.”
The well had a combined concentration of 32 parts per trillion of the two most-studied PFAS. The current federal health guideline for treated drinking water is 70 parts per trillion, but that threshold is under review.
The chemicals — of which there are thousands — have been used to make nonstick and stain-resistant materials, firefighting foams and other products. Human exposure to them has been linked to cancers and other ailments.
Initial tests of West Des Moines water in November showed it contained the two prominent PFAS in a combined concentration of 5.3 parts per trillion. A subsequent test in March did not detect either. Those tests can detect concentrations as small as 1.9 parts per trillion.
“We were pleased to see that,” said Christina Murphy, general manager of West Des Moines Water Works. “We do everything we can to mitigate the presence of those compounds.”
Two other West Des Moines wells showed contamination in lesser concentrations than the one that was shut down, and the water utility is minimizing its use of them, Murphy said. Further testing is ongoing. The utility has a total of 21 wells.
The DNR’s sampling of West Des Moines water was part of a review of about 70 community water supplies in the state in late 2021 and early 2022. A dozen of them had detectable amounts of the two most-studied PFAS.
Another round of testing of other water supplies is slated for this summer, said Corey McCoid, supervisor of the DNR’s Water Supply Operations. A list of those new test sites has not yet been finalized.
Central City, in northeast Iowa, had the highest concentration of the two PFAS in its drinking water at 61 parts per trillion. It stopped using a contaminated well, and a test in March showed that the concentration had been cut to 15 parts per trillion. City officials planned to flush the municipal water system to further expel the contamination.
The state is requiring water supplies to test their finished drinking water quarterly if they have detectable amounts of PFAS.
Ames stopped using its most-contaminated well after DNR sampling found a combined concentration of 38 parts per trillion, but its treated drinking water appeared unaffected by the change. Initial tests of the treated water showed it had the two PFAS in a combined concentration of 9.6 parts per trillion in December. In March, it was 10 parts per trillion.
Lyle Hammes, the water plant superintendent for Ames, said the city is sampling all of its 22 wells and expects test results in the coming weeks.
“Once we get all the results, we’re going to assess how we move forward,” he said.
Our stories may be republished online or in print under Creative Commons license CC BY-NC-ND 4.0. We ask that you edit only for style or to shorten, provide proper attribution and link to our web site. Please see our republishing guidelines for use of photos and graphics.