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| from EWG |
Though the level found is well below the U.S. Environmental Protection Agency’s (EPA) health advisory level of 70 ppt, that level is screening level for groundwater contamination, not a health based maximum contaminant level (MCL) for drinking water. In 2009 the EPA set the first health advisory level (HAL) for PFOA and PFOA at 400 ppt each. In 2016 EPA reduced the health advisory level to a combined 70 ppt for PFAS. They have not yet established a health based MCL. The other sites in Virginia with measured PFAS were the James River in Richmond a private well in Chincoteague, and the military bases in Norfork, Hampton and Newport News area. All these other areas have much higher measured levels of PFAS than Prince William Service Authority.
Is the level found in here in Prince William a concern? I don’t know, probably not. Some states with extensive PFAS drinking water contamination have set more health-protective limits or lower advisory levels than the EPA to protect their residents. For example, New Jersey has set a legal limit of 13 ppt for perfluorononanoic acid, or PFNA, and proposed enforceable limits of 14 ppt for PFOA and 13 ppt for PFOS. Other states such as Washington, Michigan, and North Carolina are conducting additional testing to further evaluate the extent of contamination in drinking water. Concern seems very limited for the level of PFAS found in Prince William. Still, it does bio-accumulate. The Service Authority should consider additional monitoring as WSSC Water has, and there are in home treatments that are very effective.
PFAS dissolves in water, and combined with their chemical properties means that traditional drinking water treatment technologies used at water treatment plants are not able to remove them. However, activated carbon adsorption, ion exchange resins, and high-pressure membranes have been found to remove PFAS from drinking water, especially Perfluorooctanoic acid (PFOA) and Perfluorooctanesulfonic acid (PFOS), which have been the most studied of these chemicals.
NSF, UL, Water Quality Association or CSA Group certification are organizations that certify water treatment products. To earn certification, a manufacturer must undergo testing to confirm that the unit meets all chemical reduction claims and is structurally sound. NSF International, a testing and certification company, developed a certification standard for removal of PFOS and PFOA in 2016. The certification requires that the filter reduce these two chemicals only to EPA’s health advisory level of 70 ppt, but that level may not satisfy your current concerns. Units that are labeled as effective for removing pesticides (such as Aldrin) and volatile organic compounds should also be effective for PFOA and other PFCs.
Activated carbon treatment is the most studied treatment for PFAS removal. Activated carbon is commonly used to adsorb natural organic compounds, taste and odor compounds, and synthetic organic chemicals in drinking water treatment systems.
Activated carbon or commonly granulated activated carbon (GAC) has been shown to effectively remove PFAS from drinking water when it is used in a flow through filter mode after particulates have already been removed. EPA says, “GAC can be 100 % effective for a period of time, depending on the type of carbon used, the depth of the bed of carbon, flow rate of the water, the specific PFAS you need to remove, temperature, and the degree and type of organic matter as well as other contaminants, or constituents, in the water.”
Another treatment option is anion exchange treatment. There are two broad categories of ion exchange resins: cationic and anionic. Only the positively charged anion exchange resins (AER) are effective for removing negatively charged contaminants, like PFAS. Water softeners remove cations (positively charged ions such as calcium and magnesium) and are not what you need to remove PFAS.
AER has shown to have a high capacity for many PFAS; however, it is typically more expensive than activated carbon filtration. According to the EPA “of the different types of AER resins, perhaps the most promising is an AER in a single use mode followed by incineration of the resin. One benefit of this treatment technology is that there is no need for resin regeneration so there is no contaminant waste stream to handle, treat, or dispose.” It is unclear what the regulatory requirements are for the PFAS waste stream.
The final option is high-pressure membranes, such as nanofiltration or reverse osmosis. These have been found to be extremely effective at removing PFAS.. This technology depends on membrane permeability, and reverse osmosis membranes are tighter than nanofiltration membranes. A standard difference between the two is that a nanofiltration membrane will reject hardness to a high degree, but pass salts; whereas reverse osmosis membrane will reject all salts to a high degree (which is why it’s used for desalinization). This also allows nanofiltration to remove particles and hardness while retaining minerals that reverse osmosis would likely remove.
EPA states that “research shows that these types of membranes are typically more than 90% effective at removing a wide range of PFAS, including shorter chain PFAS.” As EPA points out: “Approximately 20% of the feedwater is retained as a high-strength concentrated waste. A high-strength waste stream at 20% of the feed flow can be difficult to treat or dispose, especially for a contaminant such as PFAS...”
Overall, activated carbon filtration is the least expensive and simplest solution. It can be point of use or whole house and an added advantage is that is polishes the water leaving it tasting very good. In 2007 the state of Minnesota commissioned a study of the effectiveness of activated carbon filtration and reverse osmosis devices in removing PFAS you see the entire report at the link. they found to be effective.
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