State testing data show that several contaminants — all of which can be harmful to human health — are commonly found in the drinking water provided to residents of South Dakota, but whether the contaminants are present at unhealthful levels is a matter of ongoing debate.
In most cases, the tap water generated by the 650 drinking-water systems across the state fall well within guidelines set by the U.S. Environmental Protection Agency for safe consumption of lead, copper, nitrates, arsenic, radium, uranium, and a chlorine sanitation byproduct called trihalomethanes.
All of those chemicals, most of them known carcinogens, are consistently found in much of the drinking water tested regularly by South Dakota water system operators and reported to the state and federal governments. Except in rare cases, such as when a system failure occurs or a contaminant builds up over time, the contaminant levels fall below the legal guidelines set by the EPA.
But a national environmental group is trying to change the definition of “safe” and strengthen federal and state guidelines for what is considered “healthful” when it comes to the presence of dangerous contaminants in drinking water. In its annual report on America’s drinking water supply, released on Oct. 26, the nonprofit Environmental Working Group noted that many federal water-quality standards have not been updated in 20 or even 50 years, and that there are no legal limits whatsoever for 160 contaminants that can make their way into the American drinking-water system.
“The disturbing truth shown by the data is that when most Americans drink a glass of tap water, they’re also getting a dose of industrial or agricultural contaminants linked to cancer, harm to the brain and nervous system, changes in the growth and development of the fetus, fertility problems and/or hormone disruption,” the EWG said in a news release.
The study’s two main goals, according to Alexis Temkin, a staff toxicologist at EWG, is to provide Americans with an easy way to find recent data on the quality of their local drinking-water system and to highlight the group’s belief that contamination standards need to be updated and strengthened.
“Primarily, what we know is that ‘legal’ doesn’t necessarily mean ‘safe,’” Temkin said. “The vast majority of the utilities across the country get a passing grade by the EPA even though contaminants are almost always present.”
The EWG water-quality study is among the most comprehensive in the country, examining testing results from nearly 50,000 water systems across the U.S., including all of those in South Dakota that are regulated and subject to state testing requirements.
The EWG, however, creates its own set of safety guidelines that are based on the most stringent health guidelines and scientific data currently available, some from the state of California, which is known for its aggressive approach to protecting drinking water, Temkin said.
Based on its own safety guidelines, and not EPA legal standards, the group found that nearly all South Dakotans are consuming drinking water with contaminants at unhealthy levels.