Feb 12, 2020

New Report Explores Effectiveness of Water Filters to Remove PFAS

Researchers investigated the effectiveness of point-of-use and point-of-entry water filters in removing emerging contaminants such as PFAS

pfas, research, water filters

On February 5, researchers from Duke University and North Carolina State University published a new report investigating the effectiveness of point-of-use (POU) and point-of-entry (POE) filters in residential drinking water for removal of per- and polyfluoroalkyl substances (PFAS). The report, titled “Assessing the Effectiveness of Point-of-Use Residential Drinking Water Filters for Perfluoroalkyl Substances (PFAS),” was published in the peer-reviewed journal Environmental Science & Technology letters and marks one of the first studies to explore PFAS removal in residential settings. 

Overall, the researchers analyzed filtered water samples from homes in Chatham, Orange, Durham and Wake counties in central North Carolina and New Hanover and Brunswick counties in southeastern North Carolina, according to the report. The water samples were tested for a variety of contaminants, including three perfluoroalkal sulfonic acids (PFSAs), seven perfluoroalkyl carboxylic acids (PFCAs) and six per- and poly-fluoroalkyl ether acids (PFEAs), in addition to GenX.

“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, according to Duke University.

Overall, after testing 89 different water filters, the researchers had a few key takeaways. The researchers tests found that reverse osmosis (RO) filters and two-stage filters were some of the most effective filters at reducing PFAS levels, averaging more than 94% reduction. There, the researchers noted that the small number of two-stage filters tested warranted further testing to confirm the results. Additionally, they found that activated carbon filters removed 74% of PFAS contaminants on average; however, results varied, according to the report. The results also found PFAS removal efficiency for POE systems using activated carbon filters to vary. 

“The under-sink reverse osmosis filter is the most efficient system for removing both the PFAS contaminants prevalent in central North Carolina and the PFEAs, including GenX, found in Wilmington,” said Detlef Knappe, the professor of Civil, Construction and Environmental Engineering at North Carolina State University, whose lab teamed with Stapleton’s to conduct the study. “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.”

Despite the mixed results, the researchers also stressed the importance of changing water filters regularly to ensure continued contaminant reductions. It is also valuable to note the importance of product certification.

According to the Fayetteville Observer, there are an estimated 5,000 different types of PFAS. North Carolina is also reported to have the third-worst problems with PFAS out of all U.S. states, according to a report released last month by the Environmental Working Group analyzing U.S. EPA data. 

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