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Protecting public health and the quality of your drinking water is our top priority. Valley Water continues to track the rapidly evolving science and regulatory developments related to per- and polyfluoroalkyl substances (PFAS), and to evaluate potential impacts on local water supplies.

What are PFAS?

PFAS are a group of thousands of man-made chemicals that resist heat, oils, stains and water. They have been widely used in consumer products like nonstick cookware, stain-resistant carpets and fabrics, waterproofing clothing, and food packaging. They have also used in industrial processes and firefighting foams.

PFAS are often called “forever chemicals” because they break down very slowly and can accumulate in humans, animals and the environment. PFAS have been found in water, air, and soil worldwide. PFOA and PFOS are two common PFAS chemicals.

What are the health effects of PFAS?

A wide range of scientific studies suggest a certain level of PFAS exposure can cause adverse health effects

in humans, including reproductive and developmental effects, increased risk of cancer, increased cholesterol, reduced immunity including decreased vaccine effectiveness, interference with natural hormones, and liver damage.

How are people exposed to PFAS?

Most people have been exposed to PFAS through consumer products but drinking water can be another exposure source. The major sources of PFAS in water supplies are fire training and response sites where fire-suppressing foam was applied, industrial sites, landfills, and wastewater treatment plants/biosolids. Because of their persistence in the environment, PFAS can accumulate in water supplies.

Are there limits for PFAS in drinking water?

Not yet, but on March 14, 2023, the U.S. Environmental Protection Agency (EPA) released a proposal to limit six PFAS in drinking water by establishing a Maximum Contaminant Level (MCL) of 4 parts per trillion for PFOA and PFOS. The rule would also regulate combined amounts of four other types of PFAS chemicals (PFNA, PFHxS, PFBS, and GenX).

If the EPA rule is finalized, public water systems will need to monitor their water supply for these chemicals and ensure drinking water does not exceed these limits, which may require treatment or blending. The EPA will consider comments received during a 60-day public comment period and expects to finalize the regulations by the end of 2023.For more information, please visit

Until final regulations are established, public water systems in California continue to follow State Water Resources Control Board (State Board) guidance, which includes drinking water notification and response levels for PFOA, PFOS, PFBS, and PFHxS. Exceedance of a notification level requires water providers to notify their governing bodies, and customer notification is recommended. If a response level is exceeded, water providers must remove the source from service, provide treatment, or notify customers. For more information, please visit Over one third of public water systems tested in California have wells with at least one PFAS above a notification level.

Has local drinking water been tested for PFAS?

Yes. Valley Water's treated water supplies meet the proposed drinking water regulations as none of the six PFAS have been detected. This means that all the water supplied by Valley Water's three treatment plants to water retailers continues to meet all federal and state regulatory requirements, including this proposed regulation, and is safe to drink.  PFOA and PFOS have been detected at and just above the proposed MCL in two of three wells in Valley Water's Campbell Well Field. However, water from these emergency supply wells has never been served to water retailers or the public. Some water retailer wells are expected to be impacted if the EPA rule is adopted as proposed, which could require treatment or other actions.

The State Board and EPA continue to order PFAS testing of water supply wells throughout the state. Related results from wells in Santa Clara County are helping us better understand the presence of PFAS in local groundwater.

What if I have a private well?

Unlike public water systems, water from domestic wells is not subject to federal or state water quality regulations. To protect your health, you may want to test your drinking water for PFAS and other potential contaminants. Valley Water recommends that you use a laboratory that is certified to test drinking water.

How can PFAS in drinking water be treated?

Treatment technologies shown to be effective in removing PFAS from drinking water include granular activated carbon, high-pressure membranes (reverse osmosis/ nanofiltration), and ion exchange resin. More information can be found at:

 Are PFAS found in bottled water?

Bottled water producers are not subject to EPA drinking water regulations. The Food and Drug Administration, who regulates bottled water, evaluates EPA drinking water standards, and adopts bottled water standards as appropriate. We recommend consumers contact bottled water producers directly for information about their product’s water quality.

Are PFAS found in purified recycled water?

Valley Water is exploring the use of purified recycled water as a drought-resilient water supply for groundwater recharge or other uses. While PFAS are present in wastewater, any purified recycled water used in Santa Clara County would be treated with multiple, proven technologies including reverse osmosis, which is effective in removing PFAS. Valley Water is carefully testing these technologies at our Silicon Valley Advanced Water Purification Center to ensure purified recycled water meets or exceeds drinking water standards and protects human health and the environment.

What is Valley Water doing about PFAS?

We take our responsibility to provide safe, clean water and to protect groundwater very seriously. Valley Water has been proactive in evaluating the threat posed by PFAS through voluntary sampling and coordination with other agencies. Our water quality laboratory is accredited to test for PFAS in drinking water.

Valley Water and our water retailers use proven technologies and best practices to ensure drinking water delivered to businesses and residents meets or exceeds all drinking water standards. Valley Water continues to collaborate with regulatory agencies and water retailers to assess impacts to local supplies and to evaluate potential sources and treatment technologies. Valley Water will also continue to provide timely, transparent communication to customers and the public.


To find out more about PFAS or to submit questions or comments, please contact Vanessa De La Piedra at (408) 630-2788 or [email protected].