Water hardness in Castledawson
166 mg/L hard
Tap water in Castledawson is hard: 166 mg/L (9.7 gpg · 9.3 °dH · 16.6 °fH).
Source: NI Water, customer tap results 2024,2025 (OpenDataNI, OGL v3.0) (2025-12) · 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 | 166 mg/L |
|---|---|
| Utility | Northern Ireland Water |
How Castledawson compares
- Tap water in Castledawson is 10 % softer than the median of the 471 cities we track in the United Kingdom (185 mg/L).
- By hardness it ranks 248 of 471 in the United Kingdom (1 = hardest); 47 % of these cities have softer water.
- In Northern Ireland it is number 2 of 110 cities; the regional median is 100 mg/L.
- Nearest city with clearly softer water: Portglenone, 12 km away (124 mg/L).
Ranking of the hardest and softest water in the United Kingdom →
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 Castledawson
| Brand | Setting for this water |
|---|---|
| Bosch | H02 |
| Miele | 9 °dH |
| AEG / Electrolux | 2 |
| Beko | 3rd |
| 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 Castledawson water hard or soft?
It is hard: 166 mg/L as CaCO₃ (9.7 gpg, 9.3 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Castledawson 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 Castledawson water?
9.7 gpg, equal to 9.3 °dH, 16.6 °fH or 166 mg/L calcium carbonate.
What dishwasher salt setting should I use in Castledawson?
For 166 mg/L (9.3 °dH) check your manufacturer's table: level 4–5.
Do I need a water softener in Castledawson?
Recommended if you have a water heater, boiler or tankless unit: it saves repairs and detergent.
Source
Source: NI Water, customer tap results 2024,2025 (OpenDataNI, OGL v3.0) (2025-12). Method: own measurement. NI Water, customer tap results 2024,2025 (OpenDataNI, OGL v3.0) · Outdated figure? Tell us