California Guide

PFAS Contamination in California — What You Need to Know

California has some of the most significant PFAS contamination in the country. Here is where it has been found, what the state is doing about it, and how to protect your drinking water right now.

Last updated: April 2026 · By the PFASFilterGuide team

California PFAS Standard

Notification level: 5.1 ppt PFOA, 6.5 ppt PFOS. Response level: 10 ppt PFOA, 40 ppt PFOS.

California uses a notification and response level system while working toward enforceable MCLs. The notification level triggers public disclosure. The response level triggers removal of the water source from service. California's State Water Board has been developing MCLs since 2020 — they are expected to be among the strictest in the nation when finalized.

Known Contamination Sites

These are publicly documented PFAS detections in California. This is not a complete list — new sites are found regularly as testing expands.

Location	Source	PFAS Level
Orange County (multiple cities)	Industrial discharge + military bases	PFOS 50-200+ ppt in some wells
Sacramento / Mather area	Former Mather Air Force Base	PFOS and PFOA above response levels
Los Angeles County	Multiple industrial sources + airports	PFAS detected at dozens of water systems
Riverside / March ARB area	March Air Reserve Base AFFF use	PFOS above 40 ppt in nearby wells
San Diego / MCAS Miramar area	Marine Corps Air Station Miramar	PFAS detected in surrounding groundwater
Fresno County	Agricultural runoff + biosolids application	Emerging detections in agricultural areas

Military Base Contamination

AFFF firefighting foam used on military bases is one of the largest sources of PFAS groundwater contamination. The Department of Defense has identified these California bases:

March Air Reserve Base (Riverside)

Active investigation. Significant PFOS/PFOA in groundwater. Affected wells taken offline.

Former Mather AFB (Sacramento)

Cleanup ongoing. Contamination plume extends into residential areas.

MCAS Miramar (San Diego)

PFAS detected in monitoring wells. Assessment underway.

Edwards Air Force Base (Kern County)

PFAS detected. Remediation planning phase.

Naval Air Weapons Station China Lake

Investigation ongoing. Remote location limits residential exposure.

California PFAS Regulations

Notification levels set at 5.1 ppt PFOA and 6.5 ppt PFOS — among the lowest in the US
Response levels at 10 ppt PFOA and 40 ppt PFOS require source removal
All public water systems must monitor for PFAS under state order
Enforceable MCLs are under development and expected to be very strict
PFAS designated as a contaminant of emerging concern under Proposition 65
AB 1200 bans PFAS in food packaging (effective 2023)
SB 1044 restricts AFFF firefighting foam use (phase-out by 2028)

How to Test Your Water in California

California requires all public water systems to test for PFAS. Results are available through the State Water Board's PFAS investigation portal. If you are on a private well, California does not mandate PFAS testing — you must arrange it yourself. Some counties offer well testing programs through local environmental health departments.

Testing Options

DIY mail-in test ($150-$300)

Tap Score and SimpleLab offer PFAS-specific water tests. You collect a sample at home, mail it to a certified lab, and get results in 7-14 days. This tests your actual tap water — not just the utility report.

State testing program (free or low-cost)

Check with California State Water Resources Control Board for any free PFAS testing programs for private well owners. Some states offer testing through local health departments.

Check your utility's Consumer Confidence Report

If you are on public water, your utility publishes an annual water quality report. Search for your utility on the EPA's website or call them directly. Note: many utilities only recently started testing for PFAS, so older reports may not include it.

Recommended Filters for California Residents

Any NSF P473 certified filter removes PFAS. The right type depends on whether you rent or own, and how many taps you want filtered.

Renters / Budget

Clearly Filtered Pitcher — $80 + $60/yr filters. NSF P473. No install.

See full review

Homeowners / Kitchen

Under-sink RO system — $200-$400. Filters all drinking + cooking water at one tap.

See full review

Whole-House

SpringWell PFAS system — $1,500+. Filters every tap including showers and laundry.

See full review

Common Questions

Is my water in California contaminated with PFAS?+

Many California water systems have detected PFAS. The State Water Board maintains a PFAS investigation map showing all detections. Check the GAMA Groundwater Information System at gamagroundwater.waterboards.ca.gov for your area. If you are on a private well, testing has likely not been done unless you requested it.

What are California's PFAS limits?+

California currently uses notification levels (5.1 ppt PFOA, 6.5 ppt PFOS) and response levels (10 ppt PFOA, 40 ppt PFOS). Notification levels require public disclosure. Response levels require the contaminated source to be taken offline. Enforceable MCLs are still being developed.

Does California offer PFAS testing for well water?+

Not universally. Some counties offer well water testing programs through local environmental health departments. Contact your county health department to ask. Private lab testing through Tap Score or SimpleLab costs $150-$300 and tests your actual tap water.

Is PFAS contamination worse in Southern California?+

Southern California — especially Orange County, Los Angeles, and the Riverside/San Bernardino area — has some of the highest PFAS detections in the state due to military bases, airports, and industrial activity. But PFAS has been detected statewide, including the Bay Area and Central Valley.

Protect Your Water Now

You do not need to wait for your state to act. An NSF P473 certified filter removes PFAS from your tap water today. Start with a test to know your levels, then pick the filter that fits your home.

Best PFAS Filters How to Test Your Water