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April 24, 2024 2:25PM
April 24, 2024 14:25PM

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PFAS primer

IRWD’s drinking water is safe


IRWD drinking water does not contain PFAS (PFOS/PFOA/PFBS)

The drinking water we provide to homes, businesses and schools is safe and meets all quality standards set by both the state and federal government. IRWD water quality experts continuously monitor the water supply and conduct hundreds of laboratory tests each year from water taken from sample points throughout the IRWD service area. The test results are published by IRWD in the annual Water Quality Report, also known as the Consumer Confidence Report.


What are PFOS, PFOA, and PFBS?

Perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS), and perfluorobutane sulfonic acid (PFBS) are fluorinated organic chemicals that are part of a larger group of human-made chemicals referred to as per-and polyfluoroalkyl substances (PFAS), which are generally resistant to heat, water, and oil. They have been used extensively in consumer products such as carpets, clothing, fabrics for furniture, paper packaging for food, fire-fighting foams, and other materials (such as cookware) designed to be waterproof, stain-resistant, or nonstick.


How does PFAS get into the drinking water?

PFAS can get into drinking water when products containing them are used or spilled onto the ground or into lakes and rivers. PFAS move easily through the ground, getting into groundwater that may be used for water supplies or for private drinking water wells. Such contamination is typically localized and associated with a specific facility, such as an industrial facility where these chemicals were manufactured or used in other products, or an airfield that used the chemicals for firefighting. People can also be exposed to PFAS through food, food packaging, consumer products, and house dust.


What has been done to regulate PFAS?

Between 2000 and 2002, certain PFAS were voluntarily phased out of production in the United States by their primary manufacturer. Beginning in 2006 other manufacturers began to voluntarily limit the number of ongoing uses. Although most of the PFAS chemicals are no longer manufactured in the United States, other countries still produce PFAS and products that contain them may be imported, such as carpets, leather, apparel, textiles, paper, packaging, coatings, rubber, and plastics. Blood serum levels in the United States population for specific PFAS compounds have fallen significantly since that time; however, in some cases new PFAS compounds have been used in their place.


What are the State and Federal regulations governing PFOS/PFOA/PFBS?

In May 2016, the United States Environmental Protection Agency issued a lifetime health advisory for PFOS and PFOA for drinking water, advising municipalities that they should notify their customers of the presence of levels over 70 parts per trillion in community water supplies. EPA recommended that customer notifications include information on the increased risk to health, especially for susceptible populations.

Originally adopted in June 2018 and lowered in August 2019, California’s Office of Environmental Health Hazard Assessment recommended interim Notification Levels for PFOA (based on liver toxicity, as well as cancer risks), and for PFOS (based on immunotoxicity). After independent review of the available information on the risks, the California State Water Resources Control Board Division of Drinking Water (DDW) established Notification Levels for PFOS, PFOA, and PFBS (6.5 parts per trillion [ppt] for PFOS, 5.1 ppt for PFOA, and 500 ppt for PFBS), as well as Response Levels of 10 ppt for PFOA, 40 ppt for PFOS, and 5,000 ppt for PFBS. DDW discourages the serving of water above the Response Levels. A nanogram is also known as a “part-per-trillion,” and one nanogram per liter is the equivalent of four grains of sugar dissolved in an Olympic-sized swimming pool.


What are Notification and Response Levels?

Notification and Response Levels are precautionary health-based advisory levels established by the California DDW while further research and analysis are conducted by the state to determine the necessity of setting an enforceable drinking water maximum contaminant level (MCL). Notification Levels are based on the most sensitive known health endpoints for these compounds: lifetime cancer risk, liver toxicity, and immunotoxicity. Both the California DDW and the federal EPA have indicated their intent to publish an enforceable drinking water MCL; however, proposed MCLs for PFAS compounds are not expected until 2023. Until that process is complete, DDW has established Response Levels above which DDW discourages public water agencies from serving the water to customers and imposes strict public notice requirements. For more information, visit the California DDW website.


IRWD and DDW Statewide PFAS Testing

In June 2018, the State Water Resources Control Board Division of Drinking Water adopted Notification and Response Levels for PFOA and PFOS. These are health-based nonregulatory thresholds. IRWD proactively tested for the presence of PFOA and PFOS in August 2018. IRWD’s Well OPA-1, located near the Santiago Creek Recharge Basin, had detectable results above the Notification Levels but below the Response Level for PFOA and PFOS. IRWD voluntarily stopped serving the water from OPA-1 in September 2018 and this well has remained out of service since then.

In response to a statewide investigation of PFOA and PFOS by the Division of Drinking Water initiated in March 2019, IRWD retested its OPA-1 well twice. The monitoring results confirmed that OPA-1 remains over the Notification Levels for PFOA (15.4 and 16.3 ppt) and PFOS (23.8 and 26.2 ppt) and above the Response Level for PFOA. IRWD, in collaboration with Orange County Water District, has designed a groundwater treatment system to remove PFAS from the well water. Construction of the groundwater treatment system was awarded in 2022, and the well will be brought back online after construction of the treatment system.


What is IRWD doing to protect our drinking water from PFAS?

We are working with other water utilities and the Orange County Water District to better understand impacts in the groundwater basin and treatment technologies. We will stay abreast of regulatory developments to ensure ongoing compliance with all drinking water standards and requirements. Most importantly IRWD will continue to monitor water quality to assure that our drinking water remains safe. PFAS have been detected in water throughout the United States. To learn more about PFAS from the United States Environmental Protection Agency and the California State Water Resources Control Board, please see and


Updated: May 18, 2022