PFAS Information for Private Well Owners

Post September 10, 2025

Learn more about PFAS impacts for private well owners.

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Introduction

This page is designed for more information on PFAS for private well owners.

What are PFAS and how does PFAS get into your well?

PFAS (Per- and Polyfluoroalkyl Substances) are a large group of synthetic chemicals designed to resist heat, water and oil. PFAS are used in a wide range of industrial and consumer products such as fire-fighting foams, stain- and water-resistant clothing, carpets, cleaning products, non-stick cookware and food packaging.

PFAS have been found in air, soil and water around the world, and are persistent in the environment. Although certain PFAS are no longer manufactured in the U.S., these chemicals are still produced internationally and imported into the U.S. in consumer goods.

Unfortunately, groundwater is susceptible to pollutants including per- and polyfluoroalkyl substances, or PFAS. PFAS are a large group of human-made environmentally persistent organic compounds with properties that make many of them toxic and persistent in the environment. Since the 1940s, PFAS have been manufactured and used in a variety of industries around the globe, including in the United States. These chemicals are used in items such as adhesives, fire-fighting foams, cosmetics, paper products, and stain and water repellants.
PFAS enter the environment at sites where they are made, used, disposed of, or spilled. For example, PFAS are mobile and can be transported through rainwater run-off and enter surface water – for example lakes and ponds – or seep through the soil and migrate into large groundwater aquifers that can be important underground sources of drinking water.
For more information on PFAS, click here

(What does it signify if the PFAS concentration in my private well is higher than federal drinking water guidelines?) (How should I interpret elevated PFAS levels in my private well compared to federal drinking water standards?)( What are the implications if the PFAS levels in my private well surpass federal drinking water limits?)

It is important to note that consuming water with PFAS levels above the federal standard does not necessarily mean that adverse health effects will occur. The degree of risk from PFAS exposure depends on many factors including:

Level of the chemicals
How much a person is exposed and how long they’re exposed over time
Individual factors (like genetics and lifestyle)

Researchers are working to better understand how toxic or harmful PFAS are to people and the environment. If your water has been found to have PFAS and you have specific health concerns, you may wish to consult with your doctor.

PFAS impact to the Livermore Valley Groundwater Basin

Where in Eastern Alameda County is the highest impact? PFAS has been identified within the Livermore Valley GW Basin
Potential Sources
Zone 7 monitors PFAS within the GW Basin

PFAS in Zone 7 GW Monitoring Program

Insert your address in the map below to look at nearby wells and PFAS concentrations.
Insert map here
(Disclaimer) Results are for this particular well due to hydrogeologic conditions. Zone 7 recommends testing your well to verify individual PFAS results.

How can I test my well?

As a well owner the only way to be 100% sure if your well has PFAS is by testing, map provided above provides an estimate level of PFAS in nearby areas. If you believe to be at risk of exposure to PFAS you can get tested.

Where can I get PFAS tested?
U.S. EPA approve laboratories for fifth Unregulated Contaminant Monitoring Rule (UCMR5)

https://www.epa.gov/system/files/documents/2022-01/ucmr5-approved-lab-list.pdf
https://www.waterboards.ca.gov/pfas/docs/pfas-laboratories.pdf [LH1]

What should I do if my well contains PFAS?

How can I treat my well water from PFAS?

There are several different treatment systems that have shown to reduce levels of PFAs in drinking water. These methods include blah blah blah.. Each system has pros and cons etc. Treatment systems require maintenance and Zone 7 recommends annual testing to ensure the treatment system of choice is effective in reducing PFAS to safe levels.

Zone 7 recommends using the National Sanitation Foundation (NSF) as a resource to find the most appropriate equipment for in-home water treatment systems. NSF has multiple standards, NSF/ANSI 53 and 58 standards are the most appropriate water treatment systems for PFAS. NSF/ANSI standard 53 addresses health-related contaminants in drinking water systems. NSF/ANSI standard 58 is for Point-of-use (POU) reverse osmosis (RO) systems.

Granular Activated Carbon Contaminated water is passed through a pressure vessel or filter box containing granular activated carbon (GAC); PFAS then “sticks” to the activated carbon. When there is not enough space left for PFAS to stick to the GAC, it must be changed. GAC processes are normally located towards the end of treatment plants. In addition to removing PFAS, GAC may decrease disinfectant byproduct formation (by removing precursors), remove volatile organic compounds, as well as improve water’s color, taste, and smell. Potential GAC complications include PFAS displacement by other contaminants that are “stickier” (e.g., total organic carbon), release of certain metals (particularly arsenic, antimony, and iron); pH fluctuation; and reductions in disinfectant residual concentrations.
Anion Exchange Contaminated water is passed through a vessel containing anion exchange media, and anions from the media (typically chloride or hydroxide), are exchanged for the PFAS (much like sodium cations are exchanged for calcium or magnesium in water softeners which employ cation exchange). When the exchange anions are exhausted, the media needs to be replaced. The footprint for anion exchange equipment is typically ¼ that of GAC. Removal is strongly pH dependent and may require adjustment; better removal is generally achieved with more acidic (lower pH) water. Similar to GAC, anion exchange is normally located towards the end of treatment plants. Anion exchange also may reduce disinfectant byproduct formation (although typically less so than GAC). It may remove other unwanted anions, such as nitrate or sulfate. Corrosion control practices may need to be adjusted when using anion exchange.
Reverse osmosis and nanofiltration are high pressure membrane processes. Reverse osmosis is typically used for desalinization. Nanofiltration is a slightly lower pressure version of reverse osmosis that cannot remove small, dissolved salts but can remove larger molecules, such as PFAS. These processes split water into two streams – clean water (also known as permeate), and a contaminated stream (known as reject, concentrate, or brine). The volume of the contaminated stream is generally about 20% of the influent water and the PFAS are concentrated by a factor of roughly 5x. Membranes require cleaning to prevent scaling or fouling. Capital and operational costs of high-pressure membranes are very high compared to other treatment processes. Reverse osmosis and nanofiltration are normally placed towards Page 3 of 4 the end of a water treatment plant and are rarely chosen for single contaminant removal because of the high costs associated with them. These processes are very effective at reducing disinfection by products and can remove bacteria as well as viruses. The major challenge associated with these processes is brine disposal; available disposal options are site specific. Corrosion control is also a concern that may need to be addressed downstream from the process.

Can Point of Use or Point of Entry devices be used to meet the MCL?

Point of use (POU) or point of entry (POE) devices are building water treatment systems; POU devices treat only the water intended for direct consumption (drinking and cooking), typically at a single tap or limited number of taps and POE treatment devices are typically installed to treat all water entering a single home, business, school, or facility. POU and POE treatment systems are certified to reduce contaminants to a specific level in accordance with ANSI/NSF standards. EPA has not designated POU and POE treatment systems as compliance options because the PFAS regulations require treatment to concentrations below current ANSI/NSF certification standards for these devices. The EPA expects that the ANSI/NSF drinking water treatment certifications will be revised to demonstrate the ability of the devices to meet the EPA’s MCLs. When that happens, the EPA anticipates that POU and POE devices may become a regulatory compliance option for small systems. For more information, please see: https://www.epa.gov/system/files/documents/2024-04/water-filter-fact-sheet.pdf