PFAS Reporting: Complying with New MCLs

The new maximum contaminant levels (MCLs) for a handful of PFAS, represent the U.S. Government’s first enforceable regulatory action to address these chemical compounds. Environmental scientists expect large volumes of surface and groundwater used to supply drinking water across the U.S. will require PFAS treatment and removal to comply with the lower threshold concentrations. In their Consumer Confidence Reports (CCRs), community water systems will be required to include the level of the regulated PFAS measured in their drinking water, as well as the potential health effects of the regulated PFAS detected in violation of the rule. 

The proposed MCL for PFOA and PFOS indi­vid­u­ally is four parts per trillion (ppt), lower than that proposed by any state in the U.S. Addi­tion­ally, the proposed health-based water concen­tra­tions for the four additional PFAS are also lower than the standards set in any state, with the exception of PFBS and PFNA in Michigan and Washington State.

The EPA has proposed different monitoring require­ments for groundwater systems serving different populations. For groundwater systems serving more than 10,000 customers and all surface water systems, quarterly samples within a 12-month period are required during the initial monitoring period. However, for smaller groundwater systems serving 10,000 or fewer customers, only two semi-annual samples within 12 months are required. 

Compliance will be determined based on a running annual average (RAA), where levels below the maximum contaminant level indicate compliance and levels above indicate violation.

The EPA has also proposed trigger levels for these contaminants at one half of the proposed maximum contaminant levels (2.0 ppt for PFOA and PFOS, 5 ppt for PFNA, PFHxS, and GenX, and 0.5 for the Hazard Index. If a sample is below the trigger level, monitoring can be reduced to once every three years. However, if the sample is equal to or greater than the trigger level, quarterly monitoring must continue. 

If all samples during initial monitoring are below trigger levels, the utility can collect and submit one sample during the quarter with the highest prior concentration per 3-year compliance period. A single sample exceeding the trigger levels requires quarterly sampling and is required to be used for 1st quarter result of RAA calculation.