PFAS National Drinking Water Quality Regulations

PFAS National Drinking Water Quality Regulations

SCV Water Delivers Clean, Safe Water That You Can Trust:
Explaining National Drinking Water Quality Regulations

Ensuring that our customers receive clean, safe and reliable water is a top priority for SCV Water. Our customer-focused, highly skilled team is proud to deliver rigorously monitored and tested water to our community.

While PFAS are explored at the state and federal levels, we want to assure our customers that the water our Agency delivers to their tap currently meets all state and federal drinking water health standards.

We are committed to communicating with our customers about how we are safeguarding their water supply from PFAS every step of the way. Here is an update on what the EPA’s interim advisory means to our customers and how we are restoring our water supply from PFAS through treatment, technology and transparency.

What are PFAS compounds?

Per- and polyfluoroalkyl substances (PFAS) are a group of manufactured chemicals, including PFOA, PFOS and GenX. For more than 70 years, PFAS have been manufactured and used in various industries worldwide.

These chemicals are found in thousands of commonly used products, such as non-stick cookware, shampoo, food wrappers, firefighting foam, clothing, paints and cleaning products. Additionally, these chemicals exist in the environment due to manufacturing, product use and discharge of treated wastewater.

According to the EPA, most uses of PFOA and PFOS were voluntarily phased out by U.S. manufacturers in the mid-2000s. However, there are a limited number of ongoing uses of these chemicals.

Most people have measurable amounts of PFAS in their blood and are typically exposed to PFAS through eating food grown in contaminated water/soil or consuming food from packaging that contains PFAS; breathing air with dust particles from contaminated soil, upholstery, clothing; inhaling fabric sprays containing PFAS; or drinking contaminated water.

Which agencies regulate the safe levels for PFAS?

At the federal level, the EPA regulates the safe levels for hundreds of compounds in drinking water.

Setting drinking water regulations is a lengthy process. PFAS are part of a family of up to 5,000 chemicals, and the EPA is focused on a small number of these compounds which remain in the environment due to their persistence and the inability to degrade.

In April 2024, the EPA finalized a National Primary Drinking Water Regulation (NPDWR) that established regulatory standards for six per- and poly-fluoroalkyl substances (PFAS) in drinking water.

The health advisory level is the minimum compound concentration that may present health risks to an individual over a lifetime of exposure. Because there is uncertainty of the health effects associated with long-term exposure to PFOS and PFOA, the EPA sets lower health advisories. Sometimes, the advisory is lower than current analytical methods can detect.

In the State of California, our drinking water regulations are prepared by the Department of Drinking Water (DDW) in coordination with the Office of Health Hazard Assessment, and these agencies are also forging ahead in regulating PFAS. In 2021, the State proposed a draft of Public Health Goals for PFOA and PFOS. The low proposed levels are similar to EPA’s health advisories and will inform the State Water Board’s development of a drinking water standard.

And while PFAS and PFOA are explored at the state and federal levels, our water currently meets or surpasses all current state and federal standards for safety.

What are the current PFAS advisories for drinking water?

Federal PFAS Advisories

In April 2024, the EPA finalized a National Primary Drinking Water Regulation (NPDWR) that established regulatory standards for six PFAS in drinking water.

The updated standards set individual limits on the Maximum Allowable Concentration (MCL) in drinking water for specific chemicals: PFOA, PFOS, PFHxS, PFNA, HFPO-DA, also referred to as GenX. Additionally, a collective Hazard Index of 1 has been designated as the MCL for PFBS, PFHxS, PFNA, and HFPO-DA.

Chemical Maximum Contaminant Level Goal (MCLG) Maximum Contaminant Level (MCL)
PFOA 0 4 ppt
PFOS 0 4 ppt
PFNA 10 ppt 10 ppt
PFHxS 10 ppt 10 ppt

(GenX chemicals)

10 ppt 10 ppt
Mixture of two or more:
Hazard Index 1 Hazard Index 1


The new National Primary Drinking Water Regulation (NPDWR) mandates that the MCL for PFOA and PFOS should not exceed 4.0 parts per trillion (ppt), while PFHxS, PFNA, and HFPO-DA are each capped at 10 ppt, calculated using a running annual average. The Environmental Protection Agency (EPA) has adopted a unitless Hazard Index of 1 for regulating PFBS, PFHxS, PFNA, and HFPO-DA (GenX).


Public Water Systems Requirements

Public water systems are required to monitor for these PFAS and complete their initial monitoring by 2027. After that, they must continue with regular compliance monitoring. Starting in 2027, they must also inform the public about the PFAS levels in their drinking water.

If monitoring indicates that the levels of PFAS exceed the established MCLs, public water systems have until 2029 to implement solutions to reduce these contaminants. Additionally, starting in 2029, if there are any violations of these MCLs due to PFAS levels in drinking water, the affected public water systems must take corrective measures and notify the public of these violations.


PFAS State Advisories

Notification Level requires water agencies to notify government officials when PFAS in the water exceeds the set NL. In California, the set NL is 5.1 ppt for PFOA, 6.5 ppt for PFOS, 500 ppt for PFBS and 3 ppt for PFHxS.

Response Level requires agencies to take action for readings above 10 ppt for PFOS and 40 ppt for PFOA. These readings are compared to a quarterly running annual average (QRRA) of sampling results. PFBS's RL in California is 10 ppt for PFOA, 40 ppt for PFOS, 5,000 ppt for PFBS and 20 ppt for PFHxS.

For perspective, a part per trillion is a microscopic amount. One ppt is equal to one drop in a six-acre lake.

The QRRA means the average of sample results taken at an individual source during the previous calendar quarters. The QRRA is recalculated each quarter using the most recent four quarters of results.

If the QRRA exceeds the response level, DDW requires SCV Water to notify each customer, unless one of three actions are taken:

  • The well is removed from service
  • The water is blended with other water supplies to reduce to the concentration of the chemical
  • The chemical is removed through treatment


While the new EPA PFAS Rule does apply to all water systems, its immediate impact on SCV Water is limited. SCV Water will continue to operate under the established Maximum Contaminant Levels (MCLs). Although some wells may be affected in the short term, there is a 5-year compliance period allows for necessary adjustments. SCV Water maintains a 100% compliance rate and is committed to continuing this record of compliance.

Currently, 24 wells are offline due to PFAS contamination as we work to restore the wells’ water quality.

What are the PFAS Levels in SCV Water's drinking water?

Our drinking water is tested thousands of times before reaching our customers’ tap. In addition, we quarterly test for PFAS at our in-house lab to ensure they meet state and federal standards. Wells that exceed the state’s response levels for PFAS are removed from service.

How can I learn more about PFAS and water quality in the SCV?

Our knowledgeable team is here to answer your questions. We have many ways for you to learn more: