Updated: 11.2.20 

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?

Perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) are unregulated synthetic chemicals which are part of a larger group of chemicals referred to as Per-and polyfluoroalkyl substances (PFAS). PFAS are manmade substances that are resistant to heat, water, and oil commonly used in fire-fighting foams and a wide range of industrial and consumer products such as stain and water-resistant clothing, carpets, cleaning products, food packaging, and non-stick cookware. Exposure to these chemicals over certain levels may cause adverse health effects including effects on the liver, immune system, and thyroid, cancer, cholesterol changes, potential health effects during pregnancy.

Starting in 2000, production of PFOS was voluntarily discontinued in the United States, and by 2006 manufacturers phased out the production of PFOA through the PFOA Stewardship Program. U.S. manufacturers have since attempted to develop replacement technologies in the PFAS family. While less information is available, studies have shown the replacement technologies have a similar impact as the original substance. The U.S. Environmental Protection Agency (EPA) has issued regulations known as the Significant New Use Rules, requiring manufacturers and processors of PFAS to notify the EPA of any new uses before they are commercialized, providing the EPA oversight to review and, if necessary, place limits on manufacturers or processors. 

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?

The EPA and California State Water Resource Control Board Division of Drinking Water (DDW) recently set standards to regulate drinking water in California. Currently, PFAS are an unregulated contaminant of emerging concern. PFOA and PFOS are the most well-known and have been the primary focus of regulatory attention.

In May 2016, the EPA established a lifetime health advisory of 70 parts per trillion (ppt) for PFOA and PFOS in drinking water, either singly or combined. A “part-per-trillion” is the equivalent of a droplet of water in 20 Olympic-size swimming pools. Health advisories are non-enforceable and non-regulatory disclosures intended to offer a margin of protection for Americans from adverse health effects resulting from exposure.

DDW has established Notification Levels and Response Levels for PFOA and PFOS. Notification Levels are precautionary health-based advisory levels established by DDW while further research and analysis are conducted by DDW and the EPA to determine the necessity of regulating the contaminant by setting an enforceable drinking water maximum contaminant level (MCL). Notification Levels are based on the most sensitive known health endpoints for these compounds.If a Notification Level is exceeded, the water supplier shall notify the governing body of the customers served.If the Response Level is exceeded, the water supplier shall remove the water source from service, provide treatment, or notify customers. As of February 2020, Notification Levels has been set at 5.1 ppt for PFOA and 6.5 ppt for PFOS and Response Levels are set at 10 ppt for PFOA and 40 ppt for PFOS.

Each state has its own regulatory body to determine drinking water guidelines and standards for PFAS, resulting in several states having differing guidelines and standards from California. 

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 75% 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 25% of distributed water is sourced directly by the City’s three local groundwater wells (Wells 5, 6, and 8). 

In March 2019, DDW launched a statewide PFAS phased investigation including issuing testing orders to hundreds of drinking water sources, including Zone 7 and various cities throughout California, to identify the extent of contamination of drinking water sources in the state. The order required testing on a quarterly basis. In September 2020, DDW issued a statewide general order extending the duration of testing and increasing the public notification process.   

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 PFOA above the Notification Level for only Well 8. Test results also showed detection of PFOS above the Notification Level for all three wells, with Well 8 also above the Response Level. 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 all water quality test results are included in the City’s 2019 Consumer Confidence Report which can be found here: City’s water quality webpage

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

Zone 7’s groundwater wells tested above the Notification Level for PFOA and PFOS, with some above the Response Level for PFOS. In response, Zone 7 has been blending water wells and/or treating wells 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.

In 2019, State Assembly Bill 756 was enacted requiring water community water system or a non-transient non-community water system take a water source where the detected levels exceed the response level out of use OR provide a prescribed public notification starting January 2020. The City of Pleasanton did both in 2019 ahead of state legislative requirements and placed Well 8 on Emergency Standby Status and has not been in operation since initial testing in 2019, and provided the following public notifications:

How is the City of Pleasanton Addressing PFAS?

City Council approved a work plan that includes preparing a basis of design report to address remediation of Pleasanton’s groundwater wells utilizing granular activated carbon (GAC) or ion exchange (IX) treatment. The basis of design report will define scope of improvements at each well facility including preliminary cost estimates. Preliminary schedule estimates indicate a facility could be installed as early as 2023.

City Council Meetings

  • Additional elements of the work plan include:
  • Explore regional solutions with Zone 7 such as regional PFAS treatment facilities and/or offsetting City groundwater supply with increased purchases from Zone 7.
  • Performing PFAS testing in compliance with DDW orders and informing DDW, City Council, and customers of findings.
  • Provide public information on PFAS via City of Pleasanton website, annual Consumer Confidence Reports, Understanding PFAS brochure
  • Placed Well 8 on standby and not in use at this time to ensure City groundwater supplies remain below Response Levels.

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

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