The military and local water authorities in Horsham, Warminster and Warrington are spending millions of dollars to install 20-foot tall towers of carbon at numerous drinking wells.
About two dozen chemicals related to PFOS and PFOA also can be found in water contaminated by firefighting foam, and those chemicals slip through carbon treatment faster than the other two perfluorinated compounds.
This means the chemicals could get into drinking water if a water authority isn’t looking for them.
“If you’re treating for PFOS or PFOA only, a lot of these other chemicals are going to break through the system,” said Chris Higgins, a professor of environmental engineering at the Colorado college and the study’s lead researcher.
Most large carbon filtration systems, including those being installed locally, pass water through one carbon filtration tower, then test it for the chemicals, and then pass it through a second tower before it’s ready for drinking.
This two-tiered approach may not be as effective as previously thought, Higgins said, based on his research and other studies.
The military has agreed to pay to install carbon filtration systems for those wells.
And Warminster gets all its water from the North Wales system, according to Warminster Municipal Authority manager Tim Hagey.
Private water supplier Aqua Pennsylvania, which serves a number of communities in Bucks and Montgomery counties, said this week it would install and test carbon filtration systems on contaminated wells in Hatboro and Chalfont.
When tests on one Hatboro well and one Chalfont well showed levels approaching the EPA safe limit last year, they were taken offline.