Water hardness in Fountain Valley
12.7 gpg very hard
Tap water in Fountain Valley is very hard: 12.7 gpg (218 mg/L · 12.2 °dH · 21.8 °fH).
Source: California SWRCB Division of Drinking Water, EDT lab results, system CA3010069 (2026-01) · data checked 2026-10-19
Range across supply zones: 174–249 mg/L.
The Fountain Valley figure comes from State Water Resources Control Board lab results for the City of Fountain Valley system. The median of 48 results from 2021 to 2026, taken at 6 well points, is 217.5 mg/L as CaCO3 (12.7 gpg), with a range of 173.7 to 248.9 mg/L. This is very hard water. Scale builds quickly on heaters and fixtures.
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Water data
| Total hardness | 12.7 gpg |
|---|---|
| Utility | City Of Fountain Valley |
How Fountain Valley compares
- Tap water in Fountain Valley is 40 % harder than the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 471 of 1372 in the United States (1 = hardest); 66 % of these cities have softer water.
- In California it is number 104 of 336 cities; the regional median is 9.5 gpg.
- Nearest city with clearly softer water: Costa Mesa, 6 km away (6.4 gpg).
- Nearest city with clearly harder water: Garden Grove, 8 km away (18.5 gpg).
Ranking of the hardest and softest water in the United States →
What it means at home
- Severe scale: heater elements and washing-machine heaters fail early.
- Detergent use is very high; taps and screens coat within days.
- Dishwasher at maximum salt setting.
- An ion-exchange softener is practically essential; RO for drinking water.
How much salt will you use for softening?
Yes. At this hardness a softener pays for itself through appliance life and detergent.
Descale a coffee machine or kettle about every 1 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Fountain Valley
| Brand | Setting for this water |
|---|---|
| Bosch | H04 |
| Miele | 12 °dH |
| AEG / Electrolux | 3 |
| Beko | 3rd |
| Hoover | S2 |
| 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 Fountain Valley water hard or soft?
It is very hard: 218 mg/L as CaCO₃ (12.7 gpg, 12.2 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Fountain Valley 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 Fountain Valley water?
12.7 gpg, equal to 12.2 °dH, 21.8 °fH or 218 mg/L calcium carbonate.
What dishwasher salt setting should I use in Fountain Valley?
For 218 mg/L (12.2 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Fountain Valley?
Yes, unless you are only passing through: scale damages appliances within a few years.
Source
Source: California SWRCB Division of Drinking Water, EDT lab results, system CA3010069 (2026-01). Method: own measurement. California SWRCB Division of Drinking Water, EDT lab results, system CA3010069 · Outdated figure? Tell us