Is Oakley, 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 Diablo Water District.
Diablo Water District supplies Oakley (47,158 people).
Water system
Diablo Water District
47,158 people · Purchased surface water · EPA ID CA0710007
Buys treated water from Randall-Bold Water Treatment Plant.
| 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: 1.9 ppb at the 90th percentile (Dec 2022, 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.
Oakley homes and lead pipes
Lead service lines and lead solder were allowed until 1986, so homes from before then are the ones to check. How to check your own line.
Housing: Census American Community Survey 2020–2024 5-year estimates for Oakley city (tables B25034, B25003). Estimates for small places have a margin of error.
How nearby cities compare
| City | PFAS | Lead (90th pct.) |
|---|---|---|
| Brentwood 4 mi Brentwood Water System | None above limits | 0 ppb |
| Antioch 6 mi City of Antioch | None above limits | 0 ppb |
| Pittsburg 11 mi City of Pittsburg | None above limits | 0 ppb |
| Concord 17 mi Contra Costa Water District | None above limits | 0 ppb |
| Mountain House 18 mi City of Mountain House | None above limits | 0 ppb |
| Danville 20 mi East Bay Municipal Utility District | None above limits | 0 ppb |
Oakley ZIP codes (1)
- 94561
Questions
Is Oakley tap water safe to drink?
Diablo 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 Oakley, CA?
Diablo Water District, which serves 47,158 people.
Does Oakley tap water have PFAS?
None detected above EPA's reporting limits. Diablo Water District had no PFAS detected in EPA's 2023–2025 testing. "Not detected" means below the reporting limit (about 2 to 20 ppt), not proven zero.
Do Oakley homes have lead pipes?
Census estimates put 14% of Oakley 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. Diablo 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.