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 all watching for these chemicals in our groundwater.

The two primary chemicals we look for are PFOA (perfluorooctanoic acid) and PFOS (perfluorooctane sulfonate).

PFAS Fact Sheet (OCWD)

PFAS Briefing (AWWA)


Dating back to the 1940s, PFOA and PFOS have been commonly used to coat carpets, clothes, furniture, food packaging, cookware and other products.  We have all encountered PFOA and PFOS in our daily lives.  These chemicals were popular for their resistance to water, stains or unwanted adhesion, which made them particularly useful in cookware.  They were also used in fire-fighting foams, cleaning products and industrial uses.


In the 2000s, manufacturers began voluntarily phasing out use of PFOA and PFOS under a federal Environmental Protection Agency program.  PFOA and PFOS are no longer produced in the United States.  They continue to be produced in and imported from other countries but are being phased out, with some exemptions, under a ban put forth in 2019 under the Stockholm Convention, an international treaty covering pollutants.

What’s the issue?

Scientific studies have shown that long-term exposure to PFOA and PFOS at high levels can cause health issues, particularly for those who have weaker immune systems.  In California, the state Division of Drinking Water has what are known as a “notification level” and a “response level” for water agencies encountering PFOA and PFOS.

A notification level requires water agencies to notify government officials when a measure exceeds the notification level.  For PFOA, California’s notification level is 5.1 parts per trillion.  For PFOS, it is 6.5 parts per trillion.  As of February 6, 2020, California’s response level recommends water sources that test above 10 parts per trillion of PFOA and 40 parts per trillion of PFOS are taken out of service. 

Parts per million, billion or trillion are ways to measure tiny amounts of something in water or air.  It is a microscopic measurement: one part per trillion is the equivalent of four grains of sugar dissolved in an Olympic-size swimming pool.

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 Services Manager 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

    Phone: : 714-573-3350

  2. Water Billing

    Phone: : 714-573-3075

  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.