Water hardness in Dublin
11.9 gpg very hard
Tap water in Dublin is very hard: 11.9 gpg (203 mg/L · 11.4 °dH · 20.3 °fH).
Source: DSRSD 2025 Annual Water Quality Report (2025) · data checked 2026-10-20
Range across supply zones: 35–452 mg/L.
2 supply zones — hardness varies by neighbourhood; the figure above is the median.
Hardness by district / supply zone
| gpg | mg/L | ||
|---|---|---|---|
| Groundwater supply (Zone 7 Livermore-Amador aquifer) - treated water | 18.6 | 318 | very hard |
| Surface water supply (Zone 7 Water Agency, State Water Project) - treated water | 5.1 | 88 | moderately hard |
Dublin San Ramon Services District buys treated water from Zone 7 and its 2025 report lists two supplies. Surface water from the State Water Project averages 88 mg/L (5.1 gpg), while groundwater from the Livermore-Amador aquifer averages 318 mg/L (18.6 gpg) and ranges from 35 to 452 mg/L. The page figure is the median of these two rows, so your tap can be much softer or harder depending on the blend that day. Check the district's report before sizing a softener.
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Water data
| Total hardness | 11.9 gpg |
|---|---|
| Utility | Dublin San Ramon Services District (DSRSD) |
How Dublin compares
- Tap water in Dublin is 31 % harder than the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 519 of 1372 in the United States (1 = hardest); 62 % of these cities have softer water.
- In California it is number 120 of 336 cities; the regional median is 9.5 gpg.
- Nearest city with clearly softer water: Union City, 17 km away (7.3 gpg).
- Nearest city with clearly harder water: Pleasanton, 6 km away (20.4 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 Dublin
| Brand | Setting for this water |
|---|---|
| Bosch | H03 |
| Miele | 11 °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 Dublin water hard or soft?
It is very hard: 203 mg/L as CaCO₃ (11.9 gpg, 11.4 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Dublin 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 Dublin water?
11.9 gpg, equal to 11.4 °dH, 20.3 °fH or 203 mg/L calcium carbonate.
What dishwasher salt setting should I use in Dublin?
For 203 mg/L (11.4 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Dublin?
Yes, unless you are only passing through: scale damages appliances within a few years.
Source
Source: DSRSD 2025 Annual Water Quality Report (2025). Method: figure published by the water supplier. DSRSD 2025 Annual Water Quality Report · Outdated figure? Tell us