Water hardness in Union City
7.3 gpg hard
Tap water in Union City is hard: 7.3 gpg (125 mg/L · 7 °dH · 12.5 °fH).
Source: Alameda County Water District 2023 Water Quality Report (2023) · data checked 2026-10-20
Range across supply zones: 89–140 mg/L.
Alameda County Water District delivers blended water to Union City, mixing San Francisco supply with local wellfield water. Its 2023 report gives an average of 125 mg/L (7.3 gpg) for that blend, with a range of 89 to 140 mg/L, which is moderately hard. The report names the blended zone but not Union City by itself, so the figure is inferred from that description. It is also from 2023 and will be refreshed.
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Water data
| Total hardness | 7.3 gpg |
|---|---|
| Utility | Alameda County Water District (ACWD) |
How Union City compares
- Tap water in Union City is 19 % softer than the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 863 of 1372 in the United States (1 = hardest); 37 % of these cities have softer water.
- In California it is number 224 of 336 cities; the regional median is 9.5 gpg.
- Nearest city with clearly softer water: Hayward, 8 km away (3.5 gpg).
- Nearest city with clearly harder water: Pleasanton, 14 km away (20.4 gpg).
Ranking of the hardest and softest water in the United States →
What it means at home
- Fast scale on taps, shower screens and kettle; white spots on glassware.
- Water heater: efficiency loss and element failures within years if unprotected.
- Dry skin and dull hair after showering are common.
- Softener recommended; jug or reverse osmosis for drinking.
How much salt will you use for softening?
Recommended, especially with a heater or boiler: scale cuts efficiency and shortens its life.
Descale a coffee machine or kettle about every 2 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Union City
| Brand | Setting for this water |
|---|---|
| Bosch | H01 |
| Miele | 7 °dH |
| AEG / Electrolux | 2 |
| Beko | 2nd |
| Hoover | S1 |
| LG | H2 |
From each brand's manual for the model family named in the source; your model may differ, so check its manual. All brands and how to change the setting →
FAQ
Is Union City water hard or soft?
It is hard: 125 mg/L as CaCO₃ (7.3 gpg, 7 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Union City safe to drink?
Hardness is not a health issue; it is about limescale, taste and appliances. Mains water must meet national drinking-water standards. USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
How many grains per gallon is Union City water?
7.3 gpg, equal to 7 °dH, 12.5 °fH or 125 mg/L calcium carbonate.
What dishwasher salt setting should I use in Union City?
For 125 mg/L (7 °dH) check your manufacturer's table: level 4–5.
Do I need a water softener in Union City?
Recommended if you have a water heater, boiler or tankless unit: it saves repairs and detergent.
Source
Source: Alameda County Water District 2023 Water Quality Report (2023). Method: figure published by the water supplier. Alameda County Water District 2023 Water Quality Report · Outdated figure? Tell us