Review of Iowa drinking water finds dozens of contaminants

There is widespread, problematic contamination of municipal tap water in Iowa, according to an environmental group that has adopted stringent standards for water safety.

Most Iowa municipal water systems are in compliance with federal regulations, however.

The Environmental Working Group, based in Washington, D.C., released its latest review of water utilities this week. It concluded that most of Iowa’s 1,084 utilities produce drinking water that has unsafe levels of multiple contaminants, many of which are byproducts of the water treatment process.

The organization is highly critical of drinking water oversight by the U.S. Environmental Protection Agency and calls for stricter standards and federal funding to improve water quality.

“The EPA has become very good at constantly reassuring the public that all is well with the water coming out of their taps,” said Ken Cook, president of the environmental group. “That message is music to the ears of polluters who’ve fouled source waters and water utilities wary of treatment and infrastructure costs.”

Some of the contaminants were found to be above the legal limit in a handful of tap water systems, including radium at seven water utilities, arsenic at four and selenium at one. Other contaminants that were within the legal limit but exceeded the environmental group’s standards were widespread.

Residents can find reports about their drinking water based on zip code at the Environmental Working Group’s online database, which is a collection of data provided by the Iowa Department of Natural Resources.

Regulations are based on ‘acceptable level of risk’

But temper your reactions, said David Cwiertny, director of the Center for Health Effects of Environmental Contamination at the University of Iowa.

“It’s an important message, but I worry that the message gets a little lost because people are putting in their zip code and are being told that their water providers are giving them unsafe water,” he said. “It’s impossible to treat water to zero (contaminants). Our whole regulatory framework is based on an acceptable level of risk. … We’re trying to thread this needle for what’s acceptable for health outcomes and what’s affordable.”

The Environmental Working Group’s analysis found widespread, elevated levels of at least six contaminants that result from chlorine and other disinfectants that are used to treat tap water.

For example, a group of those contaminants called trihalomethanes — which have been linked to certain cancers — were detected in water from about 750 utilities. The environmental group uses a safety guideline of 0.15 parts per billion for those chemicals, whereas the EPA’s limit is 80 parts per billion. All of the 750 utilities were within the legal limit but exceeded the environmental group’s standard.

“Their standards do not take into account technical feasibility or the cost of treatment,” Corey McCoid, supervisor of the Iowa DNR’s water supply operations, said in response to the group’s report. “The Iowa DNR acknowledges that people may be concerned by the EWG news but wants the public to know that we are committed to public health protection.”

Disinfection is required by law

Des Moines Water Works, which provides drinking water to about 600,000 people in central Iowa, said its lab performs in excess of 100 water tests each day to ensure the tap water it produces meets federal and state requirements.

“Disinfection is critically important to protect public health, and it is required by law,” Water Works officials told Iowa Capital Dispatch. “The levels of acceptable disinfection byproducts identified by Environmental Working Group are significantly lower than federal regulations require.”

The most widespread contaminant found in Iowa drinking water aside from those that are the results of the treatment processes was nitrate, which can leach from fertilized crop fields into rivers that are sources of drinking water.

The federal limit for nitrate is 10 parts per million, whereas the environmental group uses a safety guideline of 0.14 parts per million. Again, all of the utilities were within the legal limit, but about 690 exceeded the environmental group’s guideline.

Cwiertny agrees that the federal limit is too high and that recent research suggests it should be halved to 5 parts per million due to evidence of adverse chronic health effects.

“There’s a need to have a conversation about our standards,” he said. “What the water providers are doing, they’re doing their best to meet the law.”