Since new regulations for perfluoroalkyl and polyfluoroalkyl substances (PFAS) were established by the Mass. Department of Environmental Protection (MassDEP) in 2021, the Acton Water District has issued several advisories that include the words “consumers in a sensitive subgroup are advised not to consume, drink, or cook with water when the level of PFAS6 is above 20 ng/L”. This directive has prompted a number of homeowners to consider the installation of a home filtration system, but since the water supplied to Acton residents only infrequently exceeds the State’s limit on these contaminants it is not necessary to spend a large amount of money to achieve an extra measure of protection. Filters that are effective in removing PFAS are certified by the National Sanitation Foundation (NSF), and consumers should verify that the product complies with the ANSI/53 or ANSI/58 standards. A list of NSF certified filters can be found at
The following information is also important. The MassDEP regulation of 20 parts per trillion and the U.S. Environmental Protection Agency (EPA) proposed regulation of 4 parts per trillion are relatively new. Although NSF-certified filters for home use have a demonstrated ability to remove PFAS, this certification does not guarantee that the treated water will comply with the new purity requirements. Actual contaminant levels following filtration cannot be determined without an expensive test (about $300) and, to maintain performance, the internal filter cartridges must be replaced regularly. Finally, it’s important to understand that only a fraction of our daily exposure to PFAS is attributed to drinking water. While exposure ratios for Acton residents have not been measured, the EPA and MassDEP assume a 20% fraction for drinking water and assign most of the remaining exposure to food and food packaging. All of these factors should be considered when considering the purchase of a home filtration system for PFAS removal.
Types of Filter Installations
Whole-House Filters – The most expensive installation is a point-of-entry filter that treats all of the water that enters the house. These systems can be customized to remove a wide variety of chemical contaminants, heavy metals, and particulates. Installation is usually performed by a licensed plumber, and the total cost typically exceeds $1,000. Replacement cartridges may cost as much as $200.
Under-Sink Filters – Since only about 10% off the water that enters a house is actually consumed as drinking water, point-of-use filters represent a cost-effective option for PFAS removal. The cost will depend on the complexity and type of filtration, but NSF certified units can be purchased for about $300. Replacement cartridge prices are in the $50 to $100 range.
Pitcher Filters – Compact counter-top filtration units that can be automatically or manually filled have recently become available for PFAS removal, and these products represent the least expensive treatment alternative. Prices for the pitchers are in the $100 range, but the removable filter cartridges may need to be replaced frequently at a cost of about $50. Over the long term, this option is likely to be more economical than the purchase of bottled water.
Filtration Technologies
GAC Filtration – Granular activated carbon is a filtration media that has been widely used to remove chemicals and particulates in drinking water. Contaminants adhere to the carbon media and are efficiently removed from the input water stream. Since the number of adsorption sites is limited, the lifetime of the filter cartridge will depend on the contaminant load and is not easily determined without regular testing. Regulations relating to filter disposal are still being reviewed by the MassDEP and the EPA.
Reverse Osmosis- These filters employ a porous membrane that segregates the input water stream into two outputs, one of which is the treated water and another that contains the extracted contaminants. Studies have shown that reverse osmosis is more effective than GAC in removing PFAS, but this method has two serious drawbacks. First, it is very inefficient in terms of water use, since the contaminated output stream comprises 75% of the input water volume. Second, according to Massachusetts law it is illegal to discharge the contaminated water stream from a reverse osmosis system to a Title 5 septic system, which would preclude the use of this filtration technology for most of the homes in Acton. Regulations for this type of discharge into the Town’s sewer system are still under review.
Ongoing PFAS Remediation Efforts at the Acton Water District
Because PFAS chemicals have been used to manufacture a wide range of consumer products for over 50 years, trace amounts of these contaminants have been detected at the parts per trillion level in water supplies throughout the world. The new MassDEP drinking water regulations for PFAS are far more stringent than those placed on any other contaminant (almost 1000 times lower than the EPA regulation for arsenic), and warnings must be sent to water users whenever the specified limits are exceeded by even a small amount. The Acton Water District has expended significant time and monetary resources in the past two years to initiate the capital improvements needed to comply with the current MassDEP and anticipated Food and Drug Administration regulations. Full compliance will require substantial upgrades to each of the Water District’s three treatment facilities.
