The Essential Environmental & Energy Blog

“I never drink water. I’m afraid that it will become habit forming”

– W.C Fields

Many of us take safe drinking water from our taps for granted. But how do we know whether our water is safe to drink? Who determines what “safe” even means? Under the Safe Drinking Water Act (SDWA), the Environmental Protection Agency (EPA) is charged with setting national standards for drinking water for a variety of naturally occurring and man-made contaminants.

Those of us in Southeastern Michigan have recently read reports of Flint’s water system failure in which a switch from Detroit Water and Sewerage Department water resulted in unacceptable amounts of lead being present in drinking water. Lead in drinking water is one contaminant that is regulated by the SDWA. But given that there are millions of possible contaminants in water and EPA only regulates 114 of them, how do we decide which substances to regulate?

The SDWA requires the EPA to identify no more than 30 unregulated contaminants to monitor study and determine whether they should be regulated every five years. These contaminants are ones that are not regulated, but are known or expected to be present in drinking water. This list of substances, known as the Contaminant Candidate List (CCL), identifies contaminants that may possibly have negative health effects.

After studying these contaminants, the EPA evaluates the results of the study and makes a “Regulatory Determination” which establishes whether at least five of the CCL contaminants require regulation.

The EPA decides whether or not to regulate a particular contaminant using the following factors: can they have an adverse effect on human health; do they occur with such frequency at levels that could pose potential health problems; and whether the regulation of the contaminants represents a meaningful opportunity to reduce risks to public health.

On Dec. 11, the EPA published its latest list of substances it proposes to study beginning in 2018 through 2020. It developed the list by looking at contaminants identified in past reviews and after discussions with a variety of stakeholders, like state and local regulators, public water entities, environmental organizations and laboratories

The contaminants it chose to investigate include 10 contaminants created by algal growths in water sources (known as cyanotoxins), two metals, eight pesticides, three acid groups of disinfectant byproducts, three types of alcohols and three semivolatile organic compounds. Those entities covered by the proposed rule include systems that serve populations larger than 10,000 people and a “representative sample” of those that serve fewer than 10,000 people.

Looking at that list, one has to think, “Wait, what? You mean that stuff is in my water and is NOT regulated?! And there’s other stuff that could be in there that they’re not even looking at?!”

Obviously, the universe of potential contaminants is quite huge and the resources to investigate them and determine which present potential health issues are not infinite. And Congress only allows the EPA to investigate no more than 30 potential contaminants every five years to identify which substances to add to those already regulated. The EPA also identified substances that it considered to add to the 30 on the proposed CLL, but did not include in the current list.

The public has a voice in deciding which 30 substances the EPA should investigate. It has conducted several meetings and webinars to get input on this list, and another is scheduled for Jan. 10. Also, the EPA is soliciting public comments with instructions on how to deliver those comments at epa.gov.