Is Costa Mesa, CA tap water safe?
Data: U.S. EPA · How we read the data · How we check it
Summary
No federal limits exceeded in EPA data for Irvine Ranch Water District. 2 PFAS were detected below the limits.
2 public water systems serve parts of Costa Mesa. The largest, Irvine Ranch Water District, serves 450,323 people. Your water bill names your system.
Largest system
Irvine Ranch Water District
450,323 people · Surface water · EPA ID CA3010092
Buys treated water from City of Newport Beach, Trabuco Canyon Water District, Joint Regional Water Supply System, Laguna Beach County Water District, City of Orange, East Orange County Water District – Wz, South Coast Water District, Santa Margarita Water District, Mesa Water District, City of Tustin, El Toro Water District, Metropolitan Water District of SO. Cal..
| PFAS | Highest average | Limit |
|---|---|---|
| PFOA Not detected | – | 4 ppt |
| PFOS Not detected | – | 4 ppt |
| PFHxS Not detected | – | 10 ppt |
| PFNA Not detected | – | 10 ppt |
| HFPO-DA (GenX) Not detected | – | 10 ppt |
ppt = parts per trillion. "Highest average" is the highest average at any of the system's entry points, the way EPA compares results with the limits.
Lead: 0 ppb at the 90th percentile (Dec 2025, and 9 in 10 homes sampled were at or below it) Below action level
Health-based violations since 2016: 0
Across California, 129 of 691 water systems EPA tested had PFAS above a 2024 federal limit, and 26 systems were above the lead action level in results from the last five years. California results.
Costa Mesa homes and lead pipes
Lead service lines and lead solder were allowed until 1986, so homes from before then are the ones to check. Renting? Ask your landlord what the service line is made of, because it's their pipe to replace. How to check your own line.
Housing: Census American Community Survey 2020–2024 5-year estimates for Costa Mesa city (tables B25034, B25003). Estimates for small places have a margin of error.
Other water systems serving Costa Mesa
How nearby cities compare
| City | PFAS | Lead (90th pct.) |
|---|---|---|
| Fountain Valley 4 mi City of Fountain Valley | None above limits | 6 ppb |
| Newport Beach 5 mi Irvine Ranch Water District | None above limits | 0 ppb |
| Santa Ana 5 mi City of Santa Ana | Above limit | 0 ppb |
| Huntington Beach 6 mi City of Huntington Beach | Above limit | 0 ppb |
| Tustin 7 mi Irvine Ranch Water District | None above limits | 0 ppb |
| Westminster 8 mi City of Westminster | Above limit | 4.7 ppb |
Costa Mesa ZIP codes (2)
- 92626
- 92627
Questions
Is Costa Mesa tap water safe to drink?
Irvine Ranch Water District has had no health-based violations since 2016. Utility data can't show lead from your own pipes: if your home was built before 1986, test your tap. Your utility's annual Consumer Confidence Report is the official summary.
Who supplies water in Costa Mesa, CA?
2 public water systems serve parts of Costa Mesa. The largest is Irvine Ranch Water District (450,323 people). Your water bill names your system. The EPA ID is also on your utility's Consumer Confidence Report.
Does Costa Mesa tap water have PFAS?
Irvine Ranch Water District had 2 PFAS detected at least once in EPA's 2023–2025 testing, all with averages below the federal limits.
Do Costa Mesa homes have lead pipes?
Census estimates put 68% of Costa Mesa homes as built before 1980 (California: 56%). Lead service lines and lead solder were allowed until 1986, so older homes are more likely to have them. Irvine Ranch Water District's service line inventory says what your line is made of. The only way to know for your home is to check the line where it enters the house and test your tap.
Source: U.S. EPA drinking water records and PFAS testing (UCMR 5). How we read the data.