Massachusetts is establishing a drinking water limit of 20 ppt for six PFAS, combined. Final regulations are anticipated to be published in the Massachusetts Register on October 2, 2020. As we previously reported, the Massachusetts Department of Environmental Protection (MassDEP) proposed the limit for PFAS in drinking water in December 2019 at the same time as soil and groundwater standards were finalized under the Massachusetts Waste Site Cleanup program.

The Standard

MassDEP is establishing a Maximum Contaminant Level (MCL) of 20 nanograms per liter (ng/L) or ppt for the sum of the following six PFAS (“PFAS-6”):

• Perfluorooctanesulfonic acid (PFOS),

• Perfluorooctanoic acid (PFOA),

• Perfluorodecanoic acid (PFDA),

• Perfluoroheptanoic acid (PFHpA),

• Perfluorohexane sulfonic acid (PFHxS), and

• Perfluorononanoic acid (PFNA). 

This MCL will apply to all public water systems except for transient non-community public water systems. Transient non-community public water systems are smaller water systems that typically do not serve the same people every day. Transient non-community public water systems are typically found at restaurants, motels, campgrounds, parks, and golf courses. Instead of the MCL, these systems will be subject to a site-specific health assessment if elevated levels of PFAS are identified. MassDEP has indicated that a standard has not been set for this group because it is a highly variable group of water supplies. 

Testing of Public Water Systems 

The regulations require that all public water systems monitor for PFAS. When monitoring must begin is staggered based on the type of system and system size, as follows:

Monitoring is initially required for four consecutive quarters, in the first month of each quarter, although MassDEP may issue a waiver to reduce the required monitoring to two quarters. 

Monitoring must be done using EPA Method 537 or 537.1, which can analyze for more than the regulated PFAS compounds. All PFAS that can be analyzed by the chosen method must be reported by the laboratory, and reported to MassDEP. EPA methods 537 and 537.1 can identify the following PFAS:

In its responses to comments, MassDEP indicated it will consider including EPA Method 533, which can analyze for 11 additional PFAS, in a subsequent amendment. 

Impacts of Detections

Detection of PFAS in a public water supply triggers confirmatory sampling. If PFAS-6 is confirmed above 10 ppt, the frequency of monitoring increases to monthly. If the average of the sample and the confirmatory sample exceeds 20 ppt, notice must be provided to all persons who are served by the affected water system. 

If the average of monthly samples over a quarter is above 20 ppt for PFAS-6, the MCL is exceeded. In that event, the public water system must take action to come back into compliance. This could include taking a source of water offline, blending several sources of water, or treating the water.

Triennial Review

The regulations require MassDEP to evaluate relevant developments in the science, assessment, and regulation of PFAS once every three years, beginning not later than December 31, 2023, to determine whether the MCL should be amended.

The Upshot

Massachusetts is joining a small number of states that have established an MCL for PFAS. This puts Massachusetts ahead of US EPA’s regulatory process under the federal Safe Drinking Water Act. Only time will tell if Massachusetts has moved too quickly.