Water hardness in Fremont
6.3 gpg moderately hard
Tap water in Fremont is moderately hard: 6.3 gpg (108 mg/L · 6 °dH · 10.8 °fH).
Source: Alameda County Water District 2023 Water Quality Information (2023) · data checked 2026-10-19
Range across supply zones: 42–140 mg/L.
2 supply zones — hardness varies by neighbourhood; the figure above is the median.
Hardness by district / supply zone
| gpg | mg/L | ||
|---|---|---|---|
| central and south Fremont (treated surface water) | 5.3 | 90 | moderately hard |
| north Fremont, Union City and parts of Newark (blended) | 7.3 | 125 | hard |
Alameda County Water District splits Fremont into two supplies. Treated surface water serves central and south Fremont at 90 mg/L (5.3 gpg), and a blend with purchased San Francisco water and local wells serves north Fremont, Union City and parts of Newark at 125 mg/L (7.3 gpg). The page shows the median of 107.5 mg/L (6.3 gpg) and relies on 2023 data, the oldest in this batch, so a newer report may differ.
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Water data
| Total hardness | 6.3 gpg |
|---|---|
| Utility | Alameda County Water District (ACWD) |
How Fremont compares
- Tap water in Fremont is 31 % softer than the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 980 of 1372 in the United States (1 = hardest); 29 % of these cities have softer water.
- In California it is number 245 of 336 cities; the regional median is 9.5 gpg.
- Nearest city with clearly softer water: Hayward, 13 km away (3.5 gpg).
- Nearest city with clearly harder water: Pleasanton, 16 km away (20.4 gpg).
Ranking of the hardest and softest water in the United States →
What it means at home
- Visible kettle scale every few weeks; vinegar or citric acid is enough.
- Water heater and washing machine: some long-term scale; a scale inhibitor slows it.
- Dishwasher: medium salt setting.
- Softener optional; pays off mainly with a gas boiler or tankless heater.
How much salt will you use for softening?
Optional. A scale inhibitor or a small softener protects the heater; soap savings are modest.
Descale a coffee machine or kettle about every 3 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Fremont
| Brand | Setting for this water |
|---|---|
| Bosch | H00 |
| Miele | 6 °dH |
| AEG / Electrolux | 2 |
| Beko | 2nd |
| Hoover | S1 |
| LG | H1 |
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 Fremont water hard or soft?
It is moderately hard: 108 mg/L as CaCO₃ (6.3 gpg, 6 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Fremont 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 Fremont water?
6.3 gpg, equal to 6 °dH, 10.8 °fH or 108 mg/L calcium carbonate.
What dishwasher salt setting should I use in Fremont?
For 108 mg/L (6 °dH) check your manufacturer's table: level 2–3.
Do I need a water softener in Fremont?
Not essential; a scale inhibitor protects the heater cheaply.
Source
Source: Alameda County Water District 2023 Water Quality Information (2023). Method: figure published by the water supplier. Alameda County Water District 2023 Water Quality Information · Outdated figure? Tell us