PFAS in Drinking Water in California
What residents of California need to know about PFAS ("forever chemicals") in drinking water — including contamination sources, which utilities have documented violations, and how to filter PFAS from tap water.
Source: EPA SDWIS, State Water Resources Control Board, CDC · Last reviewed: 2025-01-01
Quick Answer
Is PFAS in drinking water a real concern in California?
Yes — California is one of the most PFAS-contaminated states in the country. Multiple military installations (March AFB, Travis AFB, former El Toro Marine Corps Air Station), Silicon Valley industrial facilities, and airports have caused widespread groundwater contamination. Hundreds of California public water systems have detected PFAS in some wells.
Where does PFAS come from in California?
California PFAS comes from three primary sources: military and former military bases (March AFB in Riverside County, Travis AFB in Solano County, former El Toro MCAS in Orange County), semiconductor and industrial manufacturing in Silicon Valley, and fire training areas at airports and industrial facilities. The San Gabriel Valley, Riverside/San Bernardino area, and Silicon Valley have particularly extensive contamination.
What should California residents know?
California has set its own notification levels (10 ppt for PFOA, 40 ppt for PFOS) and has required utilities to test since 2020, generating one of the most complete state PFAS datasets in the country. The new federal 4 ppt MCL will require many California utilities that previously met state notification levels to install additional treatment — a significant infrastructure cost affecting hundreds of systems.
Key Facts
| EPA MCL (PFOA/PFOS) | 4 ppt — effective April 2024 |
| California notification levels | 10 ppt PFOA, 40 ppt PFOS (testing required since 2020) |
| MCLG | Zero |
| Primary contamination sources | March AFB, Travis AFB, former El Toro MCAS, Silicon Valley industrial, San Gabriel Valley industrial |
| State regulator | State Water Resources Control Board (SWRCB) |
| Systems affected | Hundreds of California PWS have detected PFAS; dozens required to treat or take wells offline |
| Health effects | Cancer (kidney, testicular), thyroid disruption, immune effects, developmental toxicity |
| Effective treatment | Granular activated carbon (GAC) or reverse osmosis at utility scale; RO at household scale |
Why PFAS Matters in California
California has more documented PFAS-affected water systems than nearly any other state. The San Gabriel Valley alone has over 30 wells taken offline or requiring treatment due to PFAS contamination, partly from industrial sources and partly from military bases. March AFB in Riverside, Travis AFB in Solano County, and the former El Toro Marine Corps Air Station in Orange County have all generated substantial PFAS plumes. Silicon Valley's tech manufacturing legacy has also contributed industrial PFAS to groundwater in Santa Clara County. California has been a national leader in PFAS regulation, adopting notification levels well before the federal MCL.
Historical Context
The San Gabriel Valley Superfund site includes PFAS from industrial sources as one of multiple groundwater contamination layers. Baldwin Park and nearby communities have dealt with contaminated wells for decades — PFAS is the newest layer of a long-running problem. California regulators have taken these communities' cumulative exposure burden seriously under the state's environmental justice framework.
California PFAS Regulation
California State Water Resources Control Board (SWRCB) required utilities to test for PFAS beginning in 2020 — years before the federal MCL — and set notification levels of 10 ppt PFOA and 40 ppt PFOS. California has one of the most extensive PFAS datasets in the country, with hundreds of public water systems reporting detections. The state is developing its own Maximum Contaminant Levels expected to be at least as protective as the federal 4 ppt standard.
Largest California Water Utilities
No PFAS violations on record in EPA SDWIS for California utilities in our database. Browse the largest utilities to review their full water quality record.
What Are PFAS (“Forever Chemicals”)?
PFAS are a family of over 12,000 synthetic chemicals used in non-stick cookware, stain-resistant fabrics, food packaging, and AFFF firefighting foam. Their carbon-fluorine bonds do not break down in the environment or the body — hence the name “forever chemicals.” AFFF used at military bases is the single largest source of PFAS in U.S. drinking water.
Full PFAS overview — national data, health effects, all 50 statesWho Should Pay Closest Attention
Communities in the San Gabriel Valley (Baldwin Park, Azusa, Irwindale area), Inland Empire (near March AFB), Solano County (near Travis AFB), Orange County (near former El Toro), and the South Bay (near Silicon Valley industrial sites) face the highest documented risk.
Residents near military bases with AFFF use history
Private well owners near military or industrial sites
Pregnant residents and families with young children
Residents in communities with documented PFAS detections
Anyone who has consumed water above 4 ppt for an extended period
Residents near airports, fire training areas, or industrial manufacturers
How to Check Your Situation in California
- 1
Identify your water utility using the ZIP lookup below or by browsing the California utility directory on this site.
- 2
Review your utility's Consumer Confidence Report (CCR) — it must report PFAS monitoring results under UCMR5 and the new MCL.
- 3
Check the EPA's ECHO database for your utility's monitoring history. Look for PFAS, PFOA, PFOS, and related compound results.
- 4
Contact your utility directly and ask for their most recent PFAS test results and whether they are implementing treatment under the 2024 MCL.
- 5
If you use a private well near a military base, airport, or industrial facility, order a PFAS panel test from a state-certified laboratory. Tests typically cost $150–$400.
- 6
If PFAS is detected above 4 ppt in your source water, install a certified NSF/ANSI 58 reverse osmosis system or an NSF/ANSI 53-certified activated carbon filter rated for PFAS removal.
How to Remove PFAS from Tap Water
Reverse Osmosis (Best)
90–99% removal — NSF/ANSI 58 certified systems only
Certified Activated Carbon
Effective with NSF/ANSI 53 or 58 certification — verify before buying
Boiling concentrates PFAS. Standard pitcher filters and water softeners do not remove PFAS. Always verify NSF certification before purchasing.
Take Action Now
Look up your California utility's PFAS monitoring history on the PFAS Watchlist below.
If your utility has detected PFAS above 4 ppt, install an NSF/ANSI 58-certified reverse osmosis system at your drinking tap.
Private well owners near military or industrial sites should order a PFAS panel test ($150–$400 at a state-certified lab).
Request your utility's most recent Consumer Confidence Report — PFAS results must be disclosed under the new 2024 MCL.
Frequently Asked Questions
Related Pages
PFAS — National Overview
All U.S. utilities with PFAS records
California PFAS Watchlist
Live utility PFAS monitoring data
California State Overview
All utilities and water quality data
Reverse Osmosis Guide
Removes 90–99% of PFAS
Activated Carbon Filter Guide
NSF/ANSI 53/58 certified options for PFAS
Arsenic in Drinking Water
Another priority contaminant
All Contaminants
Complete reference library
Data Sources & Provenance
All data on this page is sourced from official U.S. government or public datasets.
Find Your Utility
State Regulator
State Water Resources Control Board ↗