Water hardness in Dublin
138 mg/L hard
Tap water in Dublin is hard: 138 mg/L (8 gpg · 7.7 °dH · 13.8 °fH).
Source: South Dublin County Council, Lucan Area Committee reply to Question 14 (Cllr L. O'Toole), 25 Nov 2014 (2014) · data checked 2026-10-23
Range across supply zones: 50–300 mg/L.
2 supply zones — hardness varies by neighbourhood; the figure above is the median.
Hardness by district / supply zone
| mg/L | mg/L | ||
|---|---|---|---|
| Ballymore Eustace / Ballyboden / Roundwood / Stillorgan treatment plants | 50 | 50 | soft |
| Leixlip treatment plant | 225 | 225 | very hard |
This figure is over 3 years old; hardness may have changed.
Dublin is supplied mainly from the Liffey system (Poulaphouca reservoir and the Ballymore Eustace plant), with the Vartry and Dodder sources serving other parts of the city. The figure shown, 137.5 mg/L CaCO₃, is the median across 2 supply zones, which range from 50.0 to 300.0 mg/L, so it depends on which zone your street is in. This figure dates from 2014 and may have changed. Limescale is visible on kettles, taps and heaters, and a scale-reduction filter or softener can help protect appliances.
Uisce Éireann publishes hardness by supply zone.
Water data
| Total hardness | 138 mg/L |
|---|---|
| Utility | Uisce Éireann (Irish Water); in 2014 operated by Dublin City Council |
How Dublin compares
- Tap water in Dublin is close to the median of the 1 cities we track in Ireland (138 mg/L).
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 Dublin
| Brand | Setting for this water |
|---|---|
| Bosch | H01 |
| Miele | 8 °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 Dublin water hard or soft?
It is hard: 138 mg/L as CaCO₃ (8 gpg, 7.7 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in 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. Uisce Éireann publishes hardness by supply zone.
How many grains per gallon is Dublin water?
8 gpg, equal to 7.7 °dH, 13.8 °fH or 138 mg/L calcium carbonate.
What dishwasher salt setting should I use in Dublin?
For 138 mg/L (7.7 °dH) check your manufacturer's table: level 4–5.
Do I need a water softener in Dublin?
Recommended if you have a water heater, boiler or tankless unit: it saves repairs and detergent.
Source
Source: South Dublin County Council, Lucan Area Committee reply to Question 14 (Cllr L. O'Toole), 25 Nov 2014 (2014). Method: figure published by the water supplier. South Dublin County Council, Lucan Area Committee reply to Question 14 (Cllr L. O'Toole), 25 Nov 2014 · Outdated figure? Tell us