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PFAS Regulation and Monitoring

PFAS are not currently regulated in drinking water. Because there are no federal or state standards for PFAS, there are no maximum contaminant levels (MCLs) for PFAS in drinking water systems. In 2009, the US EPA set provisional health advisories of 0.4 ug/L (micrograms per liter) for PFOA and 0.2 ug/L of PFOS in drinking water. 

In 2016, US EPA set a Lifetime Health Advisory level of 70 parts per trillion (ppt)  for PFOA and PFOS (or 0.07 ug/L), individually or combined. 

In 2018, the Office of Environmental Health Hazard Assessment set individual Notification Levels of 13 ppt for PFOS and 14 ppt for PFOA (or 0.013 and 0.014 ug/L). These notification levels are based on evidence of developmental toxicity and immunotoxicity in human and animal studies. They are recommended interim notification levels. This means that OEHHA recommends that water system managers notify consumers if concentrations of PFOS or PFOA reach or surpass these interim levels until OEHHA can determine a final recommended notification level for each compound. 

However, water systems are still not required to regularly monitor for any PFAS since they remain unregulated at the federal and state levels.

US EPA Unregulated Contaminant Monitoring 

Under the Unregulated Contaminant Monitoring Rules, US EPA collects data for chemicals that are suspected contaminants in drinking water but do not have health-based standards set under the Safe Drinking Water Act. In 2013-2015, the Third Unregulated Contaminant Monitoring Rule (UCMR3) required some water systems to test for six types of PFAS.

All public water systems serving more than 10,000 people, and 800 representative systems nationwide serving 10,000 or fewer people, were monitored during a 12-month period between January 2013 - December 2015. All samples were collected from treated water at the entry point of the distribution system. National unregulated contaminant monitoring results are publicly available. Due to the infrequency in monitoring, PFAS levels shown in our Drinking Water Maps may not reflect past or current levels.

US EPA set the Minimum Reporting Levels (MRL), the smallest concentration that can be reliably measured, for each PFAS contaminant included in the UCMR3. If a sample result was below the MRL, the water system was not required to report any data for that sample.


MRL (ug/L)













Due to the infrequency in monitoring, levels shown in the PFAS in Drinking Water Maps may not reflect past or current levels.