PFAS in Orange County Drinking Water: What the 2024 EPA Rules and OC Grand Jury Data Show

<p data-bluf="true"> The Orange County Groundwater Basin supplies 77 to 85 percent of the drinking water for north and central Orange County. Per- and polyfluoroalkyl substances (PFAS) have been detected in portions of that basin, leading the Orange County Water District (OCWD) to take 106 groundwater wells offline. As of mid-2026, the district had restored 53 wells through constructed treatment facilities, with 15 retail water agencies listed as impacted. The estimated 30-year cost of remediation is $1.8 billion, according to OCWD. When the EPA finalized new PFAS Maximum Contaminant Levels in April 2024, approximately 40 additional wells fell into the impacted category, pushing the total to roughly 100. A June 2026 Orange County Grand Jury report found that public awareness of the contamination remained limited despite years of active remediation work. </p>

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Where PFAS came from in Orange County

PFAS is a family of thousands of synthetic chemicals used in industrial processes, non-stick coatings, stain-resistant fabrics, and aqueous film-forming foam (AFFF) used in firefighting training. The compounds do not break down in the environment under normal conditions, which gives them the informal label "forever chemicals."

In Orange County, PFAS entered the groundwater basin from multiple sources over several decades. Military installations and industrial sites that used AFFF during training exercises are among the primary contributors identified in local investigations and legal proceedings. The chemicals leached into soil and migrated into the groundwater basin over time.

OCWD, which manages the Orange County Groundwater Basin, has pursued legal action against PFAS manufacturers and has advocated for legislation that directs remediation costs to the polluters rather than to ratepayers and water agencies.

The Orange County PFAS dataset

The figures below come from OCWD official communications and the June 2026 Orange County Grand Jury report titled "PFAS and Public Awareness: A Closer Look at Orange County Drinking Water."

Sources: Orange County Water District (<a href="https://www.ocwd.com/what-we-do/water-quality/pfas/" rel="nofollow noopener" target="_blank">ocwd.com/pfas</a>); Orange County Grand Jury report (<a href="https://www.ocgrandjury.org/sites/jury/files/2026-06/PFAS%20and%20Public%20Awareness%20%E2%80%93%20A%20Closer%20Look%20at%20Orange%20County%20Drinking%20Water.pdf" rel="nofollow noopener" target="_blank">ocgrandjury.org</a>).

The ten retail agencies that joined OCWD's lawsuit against PFAS manufacturers include the water divisions of Anaheim, Fullerton, Garden Grove, Orange, Tustin, and Santa Ana, as well as East Orange County Water District, Irvine Ranch Water District, Serrano Water District, and Yorba Linda Water District. (Source: <a href="https://fluoridealert.org/news/oc-water-districts-file-massive-lawsuit-over-pfas-contaminants/" rel="nofollow noopener" target="_blank">fluoridealert.org, reporting on OC water district lawsuit</a>.)

What the 2024 EPA MCL rules changed

On April 10, 2024, the EPA finalized Maximum Contaminant Levels (MCLs) for six PFAS compounds in drinking water under the Safe Drinking Water Act. These are the first legally enforceable federal limits for PFAS in tap water.

The new limits:

• PFOA: 4 parts per trillion (ppt)
• PFOS: 4 parts per trillion
• PFNA: 10 parts per trillion
• PFHxS: 10 parts per trillion
• HFPO-DA (GenX chemicals): 10 parts per trillion
• Mixture of PFNA, PFHxS, PFBS, and HFPO-DA: Hazard Index of 1

Water systems have until 2029 to complete initial monitoring and until 2031 to comply with treatment requirements.

California adopted its own state MCLs that took effect January 1, 2025. The California State Water Resources Control Board set limits at 5.1 ppt for PFOA and 6.5 ppt for PFOS. California's limits are numerically higher than the federal 4 ppt standard, so federal compliance will ultimately drive the lower threshold.

For Orange County specifically, OCWD noted that the April 2024 federal rule lowered thresholds below levels at which approximately 40 additional wells had been operating, bringing the total impacted to roughly 100. The treatment infrastructure already built for earlier impacted wells gave the district a foundation to address the additional supply more quickly.

Source: EPA PFAS National Primary Drinking Water Regulation, April 2024 (<a href="https://www.epa.gov/sdwa/and-polyfluoroalkyl-substances-pfas" rel="nofollow noopener" target="_blank">epa.gov</a>); OCWD response via Association of California Water Agencies (<a href="https://www.acwa.com/news/orange-county-water-district-swiftly-responds-to-epa-pfas-ruling/" rel="nofollow noopener" target="_blank">acwa.com</a>).

How a free water test fits into the PFAS picture

A standard in-home free water test checks for hardness, chlorine residual, pH, and sometimes total dissolved solids. These readings are useful for understanding scale buildup, taste, appliance wear, and general water chemistry. Hardness in Orange County typically runs 10 to 19 grains per gallon depending on the utility and season, which is a separate and independently important issue for most homes.

PFAS testing is a different process that a field test cannot perform. Because PFAS must be measured in parts per trillion, detection requires a state-certified laboratory using EPA Method 533 or Method 537.1. The California State Water Resources Control Board maintains a list of certified labs at <a href="https://www.waterboards.ca.gov/" rel="nofollow noopener" target="_blank">waterboards.ca.gov</a>.

If you live in north or central Orange County and your water comes from one of the impacted retailers, the practical steps are:

1. Check your retailer's Consumer Confidence Report for recent PFAS monitoring results. California utilities serving 25 or more people must publish a CCR each year by July 1. The State Water Board posts these at waterboards.ca.gov.
2. If PFAS are detected at or above the minimum reporting level, contact your retailer to confirm what treatment is in place at your specific service location.
3. If you want an independent reading, order a certified PFAS lab panel on your tap water. This is separate from a standard in-home test.

A free in-home test from Purest Water Solutions is the right starting point for understanding your water's hardness, chlorine, and TDS baseline. Our team can advise you on which next steps make sense for PFAS-specific concerns in your area.

What treatment removes PFAS at the tap

Two point-of-use technologies have well-documented PFAS removal performance, both certified by NSF International.

Reverse osmosis: A system certified to NSF/ANSI Standard 58 for PFAS removal eliminates 90 to 99 percent of PFAS from drinking water at the tap. An under-sink RO unit provides treated water at the kitchen faucet for drinking and cooking. For households in affected areas this is the most reliable option.

Activated carbon block filters: Pitcher and under-sink filters certified to NSF/ANSI Standard 53 reduce some PFAS compounds but performance varies by compound and decreases as the filter media ages. Keeping to the manufacturer's replacement schedule is critical.

For whole-home coverage, granular activated carbon systems with adequate contact time can reduce PFAS in all water throughout the house. For drinking water in areas with known PFAS detections, point-of-use RO remains the standard recommendation.

Talk to our team about reverse osmosis and whole-house water filtration options for Orange County homes.

What to do now

Most Orange County utilities are operating in compliance with current state and federal limits. The active remediation program is the reason: OCWD has been treating and restoring wells since detecting PFAS in the basin years before federal MCLs existed. The 2026 Grand Jury report noted that the work is ongoing and that homeowner awareness of the underlying contamination history is low.

Three actions worth taking:

1. Pull your utility's most recent Consumer Confidence Report and locate the PFAS monitoring section. If your utility detected PFAS above the minimum reporting level, that fact must appear in the CCR.
2. If you have young children, are pregnant, or have health conditions that make you more sensitive to contaminants, call your retailer directly to ask whether PFAS treatment is in place at your service address.
3. Schedule a free water test to understand your water's baseline. Knowing your hardness and chlorine levels matters regardless of PFAS. Our team can connect you with the right next step from there.

Call (949) 873-1129 to schedule a free water test in Orange County. Book online here.