Is Union City, 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 Alameda County Water District.
2 public water systems serve parts of Union City. The largest, Alameda County Water District, serves 344,000 people. Your water bill names your system.
Largest system
Alameda County Water District
344,000 people · Surface water · EPA ID CA0110001
Buys treated water from City of Milpitas, San Francisco Regional Water System, City of Hayward.
| 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 2024, 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.
Union City 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 Union City city (tables B25034, B25003). Estimates for small places have a margin of error.
Other water systems serving Union City
- San Francisco Regional Water System600 people · Surface water · California · reported ZIPs hereNo PFAS above limits
How nearby cities compare
| City | PFAS | Lead (90th pct.) |
|---|---|---|
| Hayward 5 mi East Bay Municipal Utility District | None above limits | 0 ppb |
| Newark 7 mi Alameda County Water District | None above limits | 0 ppb |
| Fremont 9 mi Alameda County Water District | None above limits | 0 ppb |
| Pleasanton 9 mi City of Pleasanton | Above limit | 0 ppb |
| Dublin 10 mi East Bay Municipal Utility District | None above limits | 0 ppb |
| San Leandro 11 mi East Bay Municipal Utility District | None above limits | 0 ppb |
Union City ZIP codes (1)
- 94587
Questions
Is Union City tap water safe to drink?
Alameda County 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 Union City, CA?
2 public water systems serve parts of Union City. The largest is Alameda County Water District (344,000 people). Your water bill names your system. The EPA ID is also on your utility's Consumer Confidence Report.
Does Union City tap water have PFAS?
None detected above EPA's reporting limits. Alameda County 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 Union City homes have lead pipes?
Census estimates put 52% of Union City 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. Alameda County 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.