A study released last month discovered that not all home water filtration systems are effective for removing unregulated chemicals from drinking water, and systems without the proper maintenance can make the situation worse.
The study, conducted by scientists at Duke University and North Carolina State University, discovered that not only the type of filtration system, but the location and maintenance of the system, determined whether the systems were effective in removing unregulated chemicals such as PFAS, or perfluoroalkyl substances, from water. Samples for the study were collected from residents in the Cape Fear River Basin including Pittsboro, whose drinking water collected from the Haw River has been identified as containing significant amounts of PFAS.
“Assessing the Effectiveness of Point-of-Use Residential Drinking Water Filters for Perfluoroalkyl Substances (PFAS)” — the long name for the report — is one of the first to assess the efficacy of residential water treatment systems in the removal of these types of unregulated chemicals.
“We tested 76 point-of-use filters and 13 point-of-entry or whole-house systems and found their effectiveness varied widely,” said Heather Stapleton, the Dan and Bunny Gabel Associate Professor of Environmental Health at Duke’s Nicholas School of the Environment.
Stapleton noted that the most effective systems were those that were reverse osmosis and two-stage filter systems that were installed under a kitchen sink. Carbon filters for pitchers, faucets and refrigerators were “inconsistent and unpredictable” with whole-house systems being “widely variable and in some cases actually increased PFAS levels in the water.”
“The under-sink reverse osmosis filter is the most efficient system for removing both the PFAS contaminants prevalent in central N.C. and the PFEAs, including GenX, found in Wilmington,” said Detlef Knappe, the S. James Ellen Distinguished Professor of Civil, Construction and Environmental Engineering at N.C. State. “Unfortunately, they also cost much more than other point-of-use filters. This raises concerns about environmental justice, since PFAS pollution affects more households that struggle financially than those that do not struggle.”
Knappe noted that the best way to reduce the amount of these chemicals is to work to reduce them “from the source.”
The Town of Pittsboro, prior to this study, has been working with consultants from CDM Smith to determine what type of treatment system at its water treatment, if any, would help to reduce the amount of contaminants. There is currently a pilot test of several different types of systems under way at the town’s plant. The cost of these systems range from $10 to $20 million depending on the combination of systems that works best for removing the chemicals from the water drawn from the Haw River, with system maintenance costs still unknown.
The Pittsboro Board of Commissioners has also begun discussing if there is a way to provide a credit or grant system for its residents to access under-sink filters, but those discussions are in the preliminary stages.
Reporter Casey Mann can be reached at CaseyMann@Chathamnr.com.