Union City, CA Water Safety: 55/100 (2026)
1 ZIP code · 3 water systems · Updated 2026-06-03
Public water data for Union City, CA reveals a split picture — tap water quality varies meaningfully by service area and the city's grade reflects that variability.
How Union City Compares
Data: EPA SDWIS Last verified: 2026-06-03
Key Facts for Union City Residents
- Homes built before 1986: 64% — older plumbing may contain lead solder.
- Estimated remediation: $1,600 per household.
- CDC health risk index: 9.67.
Union City's Water Providers
Residential water in Union City, CA is supplied by 3 separate utilities — not one centralized authority. Each of those providers operates under its own service territory boundary, maintains its own distribution infrastructure, and files compliance documentation with the EPA on its own timeline. Federal data counts 3 water systems in the area, with these providers collectively accounting for the dominant share of household connections.
Overview
We track water quality and home safety data for 1 ZIP code in Union City, California (population ~68,141), covering 3 community water systems serving approximately 506,994 people region-wide.
No EPA violations recorded across any ZIP codes in Union City — an excellent indicator of water quality.
Home Safety Score
Average Home Safety Score for Union City: C (55/100)
The score combines three factors:
| Factor | What It Measures |
|---|---|
| Water Quality | EPA violations and compliance history |
| Lead Levels | 90th percentile lead concentration vs EPA action level |
| Radon Risk | EPA radon zone classification |
Water Sources
Union City water systems draw from: Surface water.
Lead & Copper
- Lead data: not yet available for Union City
- 0 ZIP codes exceed the EPA lead action level
Radon Risk
Dominant radon zone: Zone 2 (Moderate Risk)
The EPA recommends testing homes in Zone 1 and Zone 2 areas for radon.
Areas with No Violations
| ZIP Code | Safety Score | System | Population |
|---|---|---|---|
| 94587 | C | ALAMEDA COUNTY WATER DISTRICT | 344,000 |
All ZIP Codes in Union City
- 94587 [C]
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Lead/copper: EPA Lead and Copper Rule sampling data
- Radon: EPA Map of Radon Zones
Updated daily.
Union City Community Health Snapshot
Source: CDC PLACES (County-level estimates). Water contamination can correlate with respiratory and chronic health conditions.
Compared to National Average
Vertical line = national average. ■ Above national · ■ Below national
Union City Infrastructure Age
With 64% of homes built before 1986, lead solder in plumbing is a potential concern. The EPA banned lead solder in 1986, but many older homes retain original plumbing.
Source: U.S. Census Bureau American Community Survey (ACS).
Housing Age Profile
While newer cities carry lower aggregate plumbing risk from lead-era construction, Union City sits firmly in the older category. The median build year of 1971 indicates that more than half the housing stock was built before 1986, when lead solder was still legally used in residential copper plumbing — and a substantial portion likely predates 1970, when lead pipes were still commonly installed for service lines. These two thresholds together define the elevated plumbing risk environment that older housing cities carry, independent of what the municipal water supply delivers to the meter.
Over half of homes in Union City were built before 1986, when lead solder was banned. Older plumbing may leach lead into drinking water, especially with corrosive water chemistry.
Source: U.S. Census Bureau ACS B25034.
How Remediation Costs Compare in Union City
In Union City, property values comfortably outpace what documented remediation typically costs — the equity share is proportionally low.
Remediation costs in Union City are relatively low compared to home values. The $800–$2,600 estimated range is a small fraction of median property value. Home values are 43% above the California average.
Union City: Lead Risk & Vulnerable Populations
Why children are most at risk: The CDC states there is no safe level of lead exposure for children. Children under 6 absorb lead more readily than adults, and even low levels can cause developmental delays, learning difficulties, and behavioral problems.
Although utility-side compliance with federal Lead and Copper requirements remains the system reference, that compliance does not extend down into interior plumbing. With 64% of Union City stock built before the solder ban and aggregate readings at or beyond the action mark, a household-level sample becomes the practical way to close that information gap.
Sources: EPA Lead and Copper Rule, U.S. Census Bureau ACS, CDC childhood lead poisoning prevention guidelines.
Union City: Flood History & Water Damage Risk
Union City's flood exposure sits in the moderate range: 25 NFIP claims on record and 100% of ZIP codes within FEMA-designated flood zones. Residents with private wells or older infrastructure have reasonable grounds to factor flood timing into their water quality awareness.
Union City has a moderate flood history with 25 FEMA claims averaging $19,970 per payout. 100% of ZIP codes fall within FEMA flood zones. Flood events can contaminate drinking water and overwhelm treatment systems.
How flooding affects water quality: Flood events can introduce sewage, agricultural runoff, and industrial chemicals into water supplies. Even after floodwaters recede, contamination can persist in wells and aging infrastructure. Flood damage can add significantly to the estimated <strong>$1,600</strong> remediation cost per household.
Residents in flood-prone areas should consider flood insurance even outside FEMA zones — over 25% of flood claims come from low-to-moderate risk areas. After any flood event, test your water before drinking.
Source: FEMA National Flood Insurance Program (NFIP) claims data, FEMA flood zone designations.
What You Can Do in Union City
- Test your water at home. City-level data shows averages — your tap may differ. NSF-certified test kits cost $20-40 and give results in days.
- Install a certified water filter. An NSF-certified pitcher or under-sink filter removes most common contaminants.
- Check your home's plumbing. With 64% of homes built before 1986, lead solder is a real possibility.
Deep Dive Reports
Detailed analysis for Union City, CA