Water hardness in Castlewellan
33 mg/L soft
Tap water in Castlewellan is soft: 33 mg/L (1.9 gpg · 1.8 °dH · 3.3 °fH).
Source: NI Water, customer tap results 2024,2025 (OpenDataNI, OGL v3.0) (2025-11) · data checked 2026-10-20
UK suppliers report mg/L CaCO₃ and often Clark degrees (1 °Clark = 14.25 mg/L).
Water data
| Total hardness | 33 mg/L |
|---|---|
| Utility | Northern Ireland Water |
How Castlewellan compares
- Tap water in Castlewellan is 82 % softer than the median of the 471 cities we track in the United Kingdom (185 mg/L).
- By hardness it ranks 421 of 471 in the United Kingdom (1 = hardest); 9 % of these cities have softer water.
- In Northern Ireland it is number 80 of 110 cities; the regional median is 100 mg/L.
- Nearest city with clearly softer water: Dundrum, 6 km away (23 mg/L).
- Nearest city with clearly harder water: Banbridge, 24 km away (97 mg/L).
Ranking of the hardest and softest water in the United Kingdom →
What it means at home
- Little or no limescale in kettles, water heaters or washing machines.
- Soap lathers easily; water does not dry skin or hair.
- Dishwasher: salt setting at minimum or off.
- No softener needed; a jug filter only changes taste.
How much salt will you use for softening?
No. Water this soft does not need softening.
Descale a coffee machine or kettle about every 6 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Castlewellan
| Brand | Setting for this water |
|---|---|
| Bosch | H00 |
| Miele | 2 °dH |
| AEG / Electrolux | 1 |
| Beko | 1st |
| Hoover | S0 |
| LG | H0 |
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 Castlewellan water hard or soft?
It is soft: 33 mg/L as CaCO₃ (1.9 gpg, 1.8 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Castlewellan safe to drink?
Hardness is not a health issue; it is about limescale, taste and appliances. Mains water must meet national drinking-water standards. UK suppliers report mg/L CaCO₃ and often Clark degrees (1 °Clark = 14.25 mg/L).
How many grains per gallon is Castlewellan water?
1.9 gpg, equal to 1.8 °dH, 3.3 °fH or 33 mg/L calcium carbonate.
What dishwasher salt setting should I use in Castlewellan?
For 33 mg/L (1.8 °dH) check your manufacturer's table: level 0–1, usually no salt.
Do I need a water softener in Castlewellan?
No. With soft water a softener adds nothing.
Source
Source: NI Water, customer tap results 2024,2025 (OpenDataNI, OGL v3.0) (2025-11). Method: own measurement. NI Water, customer tap results 2024,2025 (OpenDataNI, OGL v3.0) · Outdated figure? Tell us