What You Need to Know about Unregulated Contaminants

Is Your Tap Water Safe?

The Clean Water Act (CWA), passed in 1948 and amended in 1973, enables the U.S. Environmental Protection Agency (EPA) to regulate discharges of pollutants into waters across the U.S., as well as regulate quality standards for surface waters. The Safe Water Drinking Act (SDWA) of 1974, amended in 1986 and 1996, is the main federal law that ensures the quality of drinking water in the U.S.

Under the SDWA, the EPA regulates over 90 contaminants that can be found in drinking water from public water sources, but currently, there are many potentially dangerous ones that are unregulated. These include pesticides, disinfection byproducts, chemicals used in commerce, waterborne pathogens, pharmaceuticals, and biological toxins. Every five years, the EPA reviews a list of unregulated contaminants that are not subject to the health risks that fall under jurisdiction of the SDWA, with the goal of ensuring that drinking water continues to be safe.

The Contaminant Candidate List (CCL) includes contaminants that are currently not subject to any proposed or current national primary drinking water regulations, but are known or anticipated to occur in public water systems. Contaminants listed on the CCL may be subject to future regulation under the SDWA. Below are just a handful of chemicals and microbial contaminants included on the most recently published CCL.


  • Aluminum
  • Benzyl chloride
  • Chlorate
  • Formaldehyde
  • Methanol
  • Nitroglycerin
  • PFOA
  • PFOS
  • Urethane

Microbial Contaminants

  • Adenovirus: Virus most commonly causing respiratory illness, and less often, gastrointestinal illness.
  • Enterovirus: Group of viruses including polioviruses, coxsackieviruses, and echoviruses that may cause mild upper respiratory symptoms (a cold), a flu-like illness with fever and muscle aches, or a mild illness with a rash.
  • Hepatitis A virus: Virus that causes liver disease and jaundice, most often associated with a lack of safe water and poor sanitation.
  • Salmonella enterica: Common food- and waterborne bacterium accounting for 60% of all bacterial disease outbreaks in the U.S.

A recent study found 18 unregulated chemicals in drinking water from more than one-third of U.S. water utilities sampled nationwide. Perfluorinated chemicals, which were found most frequently, are widely used in a variety of industrial processes, including manufacture of some nonstick and stain-resistant food packaging, fabrics, and cookware. The two most common of these compounds, PFOS and PFOA, have been detected in the blood of nearly everyone in the U.S. A panel of scientists concluded that there is a “probable link” between PFOA in drinking water and high cholesterol, ulcerative colitis, thyroid disease, testicular cancer, kidney cancer, and pregnancy-induced hypertension.

Cyanotoxins are contaminants you may not be familiar with, but you have likely heard or read news reports about blue-green algae. These multiply quickly when the nutrients phosphorous or nitrogen are high (commonly from fertilizer contaminants), especially in warm, calm waters. About 400,000 Toledo, Ohio residents were without drinking water in late July 2014 when the water source from nearby Lake Erie became contaminated with blue-green algae loaded with cyanotoxins. Deadly to fish and pets, cyanotoxins can cause liver damage, dizziness, and vomiting in humans.

Although the EPA states that millions of Americans have access to safe tap water every day, you may want to use a high quality water filter—countertop, under counter, or pitcher water filter—to give yourself complete peace of mind when pouring that thirst-quenching glass of H2O. And to be safe, install a shower filter before taking that relaxing, steamy shower, or a whole-house unit to filter the potential dangers lurking in all of the water in your house.

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