Understanding PFAS

Per- and polyfluoroalkyl substances are a large family of chemicals commonly referred to as PFAS.  The City, the Orange County Water District and other agencies across Orange County are closely monitoring for these chemicals in our groundwater.

Although sampling for multiple compounds, the four primary chemicals we are monitoring are PFOA (perfluorooctanoic acid), PFOS (perfluorooctane sulfonate), PFBS (perfluorobutane sulfonate) and  PFHsX (perfluorohexane sulfonate).

PFAS Frequently Asked Questions (OCWD)

PFAS Briefing (AWWA)

CA State Water Resources Control Board Division of Drinking Water

What is PFAS

Per- and polyfluoroalkyl substances (PFAS) are a group of thousands of chemicals that are used to make carpets, clothing, fabrics for furniture, food packaging, cookware, and other materials to make them non-stick and/or resistant to water, oil, and stains. They are also used in a number of industrial processes and firefighting activities.

Two legacy long-chain PFAS, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), are no longer produced in the United States. Between 2000 and 2002, PFOS was voluntarily phased out of production in the U.S. by its primary manufacturer. In 2006, eight major companies voluntarily agreed to phase out their global production of PFOA and PFOA-related chemicals, although there are a limited number of ongoing uses. Scientists have found PFOA and PFOS in the blood of nearly all the people they tested in national monitoring surveys. Newer short-chain PFAS compounds have been introduced by the industry as replacements for PFOA and PFOS, such as perfluorobutane sulfonic acid (PFBS).

Current Advisories for PFAS

In March 2023, the U.S. EPA (EPA) announced the proposed National Primary Drinking Water Regulation (NPDWR) for six PFAS including perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorononanoic acid (PFNA), hexafluoropropylene oxide dimer acid (HFPO-DA, commonly known as GenX Chemicals), perfluorohexane sulfonic acid (PFHxS), and perfluorobutane sulfonic acid (PFBS). The proposed PFAS NPDWR does not require any actions until it is finalized.

EPA anticipates finalizing the regulation by the end of 2023. The proposed rule would require public water systems to monitor for these PFAS, notify the public of the levels of these PFAS, and reduce the levels of these PFAS in drinking water if they exceed the proposed standards.

Summary of EPA’s proposed regulations:

ChemicalNotification Level (NL)Response Level (RL)
PFOA5.1 ppt10 ppt
PFOS6.5 ppt40 ppt
PFBS500 ppt5,000 ppt
PFHxS3 ppt20 ppt

*Note that 1 ppt is roughly equivalent to one drop of water in 20 Olympic-sized pools.

State PFAS Advisories

OCWD and its PFAS-impacted retailers comply with state advisory levels for PFOA, PFOS, PFBS, and PFHxS established by the State Water Resources Control Board’s Division of Drinking Water (DDW).

Current state advisory levels are:

ChemicalNotification Level (NL)Response Level (RL)
PFOA5.1 ppt10 ppt
PFOS6.5 ppt40 ppt
PFBS500 ppt5,000 ppt
PFHxS3 ppt20 ppt

*Note: GenX has not been detected in the Basin; PFBS has been detected, but at levels far below all current state advisories and the new federal HA

Notification Levels (NL)

The NL is the level at which water agencies are required to notify local elected officials and governing bodies of the presence of contaminants in local water supplies. NLs are precautionary health-based advisory levels established by 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).

Response Levels (RL)

The RL is the level at which the state recommends the water not be served to the public without treatment or blending to reduce contaminants.

The State has issued draft Public Health Goals (PHGs) for PFOA and PFOS. Once the PHGs are finalized, DDW will use them as the basis for developing statewide enforceable drinking water regulations, a process which should take approximately two years.

What Tustin is doing?

We are working with 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, and most importantly we will continue to monitor water quality to assure that our drinking water remains safe.  PFOS and PFOA have been detected in water throughout the United States. To learn more about PFOS and PFOA please see this fact sheet.

Anyone with questions or concerns can contact Water Assistant Public Works Director, Mike Grisso at (714) 361-4719 or email mgrisso@tustinca.org.

Additional Information

Orange County Water District

Department of Drinking Water

Environmental Protection Agency

US Food and Drug Administration

  1. Water Services Division

  2. Water Billing

  3. After Hours Water Emergencies

    Emergency Phone: 714-549-6913

    For emergencies during the hours of 5:00 p.m. to 6:30 a.m.