Union City Water Hardness & Quality Report (2026)
Water Hardness
9.1 grains per gallon
Source
mixed
pH Level
8.1
neutral = 7.0
Lead
0.007 mg/L
✓ Below action level
TDS
460.6 mg/L
Est. Daily Cost
$0.42
energy & soap waste
Source: USGS Water Quality Portal · Updated 2026
0–60
mg/L
Soft
61–120
mg/L
Moderately Hard
121–180
mg/L
Hard
180+
mg/L
Very Hard
Appliance Damage Report
In Union City, your appliances are currently losing 21% efficiency due to mineral buildup.
| Appliance | In Union City | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 4.4 yrs | 8.5 yrs | -48% |
| Washing Machine | 7.8 yrs | 12 yrs | -35% |
| Water Heater | 9.3 yrs | 15 yrs | -38% |
Regional Water Comparison
How Union City compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Union City, California | 156.5 mg/L | 6.6 ppt | 🟠 Hard | mixed |
| Fremont, California | 180 mg/L | 7.3 ppt | 🔴 Very Hard | mixed |
| Newark, California | 32.5 mg/L | 2.9 ppt | 🟢 Soft | mixed |
| Hayward, California | 182 mg/L | 7.3 ppt | 🔴 Very Hard | mixed |
| Cherryland, California | 75 mg/L | 4.2 ppt | 🟡 Moderately Hard | mixed |
National Benchmark
How Union City compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Union City | 156.5 mg/L | 🟠 Moderate |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Union City's Water Unique?
Local geology and source profile
Union City, California, in southern Alameda County on the east shore of San Francisco Bay south of Fremont, draws its municipal water supply through the Alameda County Water District (ACWD), sourcing from the East Bay Municipal Utility District (EBMUD) Mokelumne River treated water (very soft Sierra Nevada source) and significantly from local Niles Cone Groundwater Basin wells in the Union City–Newark sub-basin area. ACWD is distinct from EBMUD — it manages both imported EBMUD water and local South Alameda County groundwater. Water hardness in Union City measures 156.5 mg/L — classified as hard, substantially higher than EBMUD-only served Alameda (39.5 mg/L).
Union City's hard supply (compared to adjacent EBMUD-only communities) reflects ACWD's significant local groundwater component from the Niles Cone Basin. The Niles Cone is an alluvial fan aquifer deposited by Alameda Creek from the Diablo Range (Franciscan Complex — blueschist, greenschist, serpentinite; Great Valley Sequence — calcareous turbidite sandstone and shale). The Franciscan Complex and Great Valley Sequence in the Sunol–Niles canyon area contain substantial calcium-bearing minerals (serpentinite: magnesium-calcium silicate; calcareous turbidite: calcium carbonate cement). Groundwater from the Niles Cone in Union City is significantly harder than the EBMUD Mokelumne import, raising the blended ACWD supply to 156.5 mg/L.
At 156.5 mg/L, Union City residents face regular hard water challenges. Scale deposits form on faucet aerators, showerheads, and appliances within weeks — monthly descaling with citric acid solution is standard maintenance. Alameda County Water District consistently delivers water meeting all California SWRCB and EPA Safe Drinking Water Act requirements.
Geology & Source: Mixed supply from East Bay Municipal Utility District (EBMUD) Mokelumne River aqueduct and local Niles Cone Groundwater Basin (Union City–Newark sub-basin) via the Alameda County Water District (ACWD) — the Sierra Nevada granodiorite Mokelumne watershed and the Alameda Creek–Mission Peak alluvial fan aquifer; hard supply at 156.5 mg/L in Alameda County.