What are we to do when we find PFAS in private water supply wells? (And we will...)

Posted on February 19, 2021 by Robert D. Cox, Jr.

Here in Massachusetts, public water suppliers (PWS) have begun sampling for the presence of PFAS in their water supplies in accordance with new rules set by our regulatory agency, Massachusetts Department of Environmental Protection (MassDEP). In October 2020, MassDEP issued a PFAS public drinking water standard at a Maximum Contamination Level (MassMCL) of 20 nanograms per liter (ng/L) (or parts per trillion (ppt)) – individually or for the sum of the concentrations of six specific PFAS or the “PFAS6.”[1] The regulations detail the sampling requirements and corrective actions that PWS must take when the MassMCL is exceeded, as well as the provisions for public education and notice of exceedances so that communities may be proactive in protecting their drinking water quality.

Roll-Out Schedule: 

January 1, 2021: Large PWS, serving more than 50,000 people, began compliance monitoring.

April 1, 2021: PWS serving between 10,000 and 50,000 people are to begin monitoring.

October 1, 2021: Smaller systems, serving 10,000 or fewer people begin compliance monitoring,

September 30, 2022: Transient Non-community PWS (e.g., hotels and restaurants) must collect, analyze and report sampling results.

The big concern, of course, is that many PWS will find PFAS and need to install costly treatment at the expense of other necessary system upgrades. Based on experiences in other states, widespread PFAS contamination is not expected, but the cost to an individual PWS will depend upon the extent of PFAS contamination at that PWS.  To its credit, the state has made funding available for limited sampling as well as reimbursement for the design of PFAS treatment, along with low interest loans. Clearly, if PFAS detections are widespread and at elevated levels, public funding to support PWS capital infrastructure and other financial and technical assistance associated with PFAS testing, monitoring, and remediation will be necessary.

What about private drinking water wells?  While PWS are regulated by the Safe Drinking Water Act (Massachusetts took delegation of SDWA authority in 1977) and thereby are obligated to provide safe drinking water, it’s a different story with private wells. Private wells provide drinking water to more than 500,000 Massachusetts residents, and more than 13 million US households rely on private wells for drinking water. The SDWA does not protect private wells.  Unlike PWS, the 20 ppt PFAS6 MassMCL standard does not apply to private drinking water wells.

Massachusetts does have other laws that indirectly protect the quality of the water obtained from a private water system. The owner of a private well is generally responsible for ensuring the quality of their drinking water.

MassDEP is encouraging PFAS sampling of residential wells. For 81 Massachusetts towns where 60% or more of residents are served by private wells, MassDEP is offering free PFAS sampling. Sampling is suggested if a private well is located within one to two miles of a known source of PFAS or of other water supplies where PFAS has been detected. Known PFAS sources include airfields and firefighting training areas, where Aqueous Film Forming Foam (“AFFF”) containing PFAS was in use, and certain manufacturing facilities. Because PFAS have been widely used in consumer products such as food packaging and non-stick surfaces, septic systems and landfills may also be a source of PFAS in groundwater.

Here Is The Kicker:  Although the 20 ppt PFAS6 MassMCL standard does not apply to private drinking water wells, un-permitted releases of oil and hazardous materials, including PFAS6, into the environment are regulated under our state “superfund” law, Chapter 21E and MassDEP’s regulations, known as the Massachusetts Contingency Plan (MCP).  The MCP has a “Reportable Concentration” of 20 ppt for PFAS6 in groundwater used as drinking water. As a result, homeowners who test their private well and find that PFAS6 exists in groundwater in concentrations equal to or above 20 ppt are required to notify MassDEP, undertake MCP response actions, and may find themselves subject to significant legal and financial responsibilities under Chapter 21E.

If the source of PFAS6 in the drinking water well is known, MassDEP will require the parties responsible for the contamination to take necessary action. But, if the source of PFAS6 is unknown when the homeowner receives the data results, the owner is likely to be left holding bag. Under Chapter 21E and the MCP, the homeowner has responsibility to address the contamination. MassDEP will to provide technical information on actions needed - such as installation of Point of Use (POU) or Point of Entry (POE) water treatment devices - to ensure that “safe” water is available. But these systems are generally designed to meet the USEPA’s Health Advisory of 70 ng/L (or ppt) for the sum of PFOS and PFOA, and not specifically designed to meet Massachusetts’ drinking water standard for PFAS6.

Under Chapter 21E and the MCP, MassDEP has the authority to deem the homeowner a “Potentially Responsible Party” or “PRP” and require assessment and cleanup actions to address the contamination, including actions beyond the resident’s property, in pursuit of achieving a 20 ppt PFAS6 MCP cleanup standard.

End Game:  But is that how MassDEP or any state agency should use it powers to address PFAS found in private residential water well? Of course not. Let’s hope that does not happen here. There has got to be better way to address the risk to public health when we find PFAS in private water supply wells. 


[1] The six PFAS are: perfluorooctane sulfonic acid (PFOS); perfluorooctanoic acid (PFOA); perfluorohexane sulfonic acid (PFHxS); perfluorononanoic acid (PFNA); perfluoroheptanoic acid (PFHpA); and perfluorodecanoic acid (PFDA). MassDEP abbreviates this set of six PFAS as “PFAS6.”