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Updated: 9.27.22

The City of Pleasanton delivers safe, reliable drinking water to 22,000 customers by operating in compliance with all state and federal guidelines and regulatory requirements. 

How do I learn more about Pleasanton's Water?

The City of Pleasanton is required by state regulations to inform customers where their drinking water comes from, what is in their drinking water, and any violation of safe drinking water standards that may have occurred during the past reporting period. Every year, the City prepares a Consumer Confidence Report (CCR) that provides results of any level of regulated contaminants detected and if those levels were in violation of drinking water standards. All water quality tests confirmed that water delivered to your tap, met all applicable federal and state drinking water standards without any violations.

What are PFAS?

Per- and polyfluoroalkyl substances (PFAS) are a group of thousands of chemicals that have been used since the 1940’s in making commercial products such as carpets, clothing, food packaging, and cookware due to their waterproof, stain-resistant, and nonstick properties. In addition, they have been used in fire-retarding foam and various industrial processes. 

Perfluorooctane-sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) are currently the most well-known and studied PFAS. PFOS and PFOA were mostly phased out of production between 2000 and 2006. Still, scientists have found PFOS and PFOA in the blood of nearly all people tested in recent national monitoring surveys. Newer PFAS compounds have been introduced by the industry as replacements for PFOS and PFOA.

How are People Exposed to PFAS?

PFAS can be introduced into the body through ingestion of contaminated food or liquid and inhaling or touching products with packaging treated with the substance. PFAS can contaminate drinking water supplies when products containing them are used or spilled on the ground and PFAS migrates into groundwater. Once in groundwater the substances can travel large distances and can contaminate drinking water wells. PFAS can similarly contaminate drinking water by entering lakes and rivers that are connected to drinking water supplies. The major sources of PFAS contamination in drinking water are believed to be from fire training / fire response sites, military bases, industrial sites, landfills, and wastewater treatment plants / biosolid facilities. 


How is PFAS in Drinking Water Being Regulated?

Over the past several years, the science on PFAS and its impacts to the environment and public health have prompted regulatory consideration.

The U.S. Environmental Protection Agency (EPA) has issued health advisories for certain PFAS. These health advisories can be found at the following link: EPA Health Advisories. Additionally, the EPA is in  the process of establishing federal enforceable drinking water standards for PFOA and PFOS.

The California State Water Resources Control Board (SWRCB) has also issued drinking water advisory levels for certain PFAS as noted in the table below and is pursuing advisory levels for additional PFAS. Additionally, the SWRCB is in the process of establishing enforceable drinking water standards for PFOA and PFOS.

Does the City of Pleasanton's Drinking Water Contain PFAS?

The City of Pleasanton distributes approximately 4,500 million gallons of treated water a year to 22,000 customers. Approximately 80% of that distributed water is sourced from the Zone 7 Water Agency (Zone 7) and includes local groundwater (approximately 20%) and treated surface water (approximately 80%). The other 20% of distributed water is sourced directly by the City’s three local groundwater wells (Wells 5, 6, and 8). 

In March 2019, the California State Water Resources Control Board (SWRCB) launched a statewide PFAS phased investigation including issuing testing orders to hundreds of drinking water sources, including Zone 7 and the City of Pleasanton, to identify the extent of contamination of drinking water sources in the state. The order required testing on a quarterly basis. In September 2020, SWRCB issued a statewide general order extending the duration of testing.  

A summary of PFOA and PFOS test results for Pleasanton can be found at the following link: Pleasanton PFAS Test Results

Pleasanton test results showed detection of PFOS above the Response Level for Well 8. Upon receipt of these results, the City placed Well 8 on Emergency Standby Status and has not operated since the beginning of June 2019. 

A summary of PFOA and PFOS test results for Zone 7 can be found at the following link: PFAS Test Results

Zone 7 has been blending groundwater wells and/or treating groundwater at their Mocho Groundwater Demineralization Facility to ensure that all drinking water is below Response Levels before being delivered to Pleasanton’s water distribution system. Zone 7 test results showed no detection of PFOA and PFOS in their treated surface water supplies. 

How is the City of Pleasanton Addressing PFAS?

In September 2022, the City Council authorized staff to proceed with performing a Water Supply Alternatives Study. The purpose of the study is to evaluate water supply alternatives for the portion of water supply currently sourced via the City’s local groundwater wells that contain PFAS. These alternatives include continuing to utilize the City’s local groundwater (by adding PFAS treatment or constructing new wells) or purchasing water in lieu of local groundwater pumping. These alternatives will be evaluated against multiple criteria including cost, water supply reliability, regulatory compliance, operational complexity, administration, and implementation feasibility to determine the preferred alternative.

How is Zone 7 Addressing PFAS?

Zone 7 is implementing a number of actions to address PFAS. For more information refer to

Can I Use a Home Water Treatment System to Treat PFAS?

Home water treatment can be installed to reduce levels of PFAS. Treatment can be at the point of use (POU), which is often at the kitchen sink or in the refrigerator or at the point of entry (POE), where treatment occurs for all the water entering the household. The two suggested common effective home treatment systems for reducing PFAS are granular activated carbon (GAC) treatment systems and reverse osmosis (RO) treatment systems. Considerations for each treatment system:

GAC Treatment Systems:

  • Physical filter cartridge traps contaminant(s) which is then removed and disposed of at the end of its rated lifecycle. 
  • Filter must be replaced on a regular schedule (identified by manufacturer).
  • Generally easier to install, lower initial cost, and provides more water flow then RO systems.
  • May not effectively treat shorter chain PFAS (if present) in addition to the longer chain PFAS such as PFOA and PFOS.

RO Treatment Systems:

  • Systems force water through a membrane under pressure, leaving the contaminants at the membrane.
  • Typically requires pre-filtration to be installed to remove any sediment and small particles to maximize the life and effectiveness of the membrane.
  • Membranes and any pre-filtration cartridges must be replaced on regular schedule (identified by manufacturer). 
  • Large volumes of water are wasted in the treatment process. 
  • Research has shown potential to effectively reduce shorter chain PFAS in addition to the longer chain PFAS such as PFOA and PFOS. 

The best way to know if your home treatment system is effective is to make sure that it is tested by an independent third party. The packaging for the filter will typically contain this information. This information can also usually be found on the manufacturer’s web page. Make sure that the filter has been tested using a

NFS standardized methodology such as NSF/ANSI Standard 53 Drinking Water Treatment Units

Additional information is available at:

For more information, contact the Operations Services Department by calling 925-931-5500 or by email at

Reference Documents