Water hardness in Rawmarsh
257 mg/L very hard
Tap water in Rawmarsh is very hard: 257 mg/L (15 gpg · 14.4 °dH · 25.7 °fH).
Source: Yorkshire Water — domestic drinking water quality (Stream open data, CC BY) (2026-08) · data checked 2026-10-19
Range across supply zones: 227–313 mg/L.
Rawmarsh is supplied by Yorkshire Water, whose supply comes from a mix of upland reservoirs, rivers and boreholes; the company says water in the west comes off the moors while the east relies mostly on boreholes and groundwater. Reported hardness is 257.2 mg/L CaCO₃, ranging from 226.9 to 313.2 mg/L between supply zones. The harder supply reflects borehole and groundwater sources, which pick up calcium and magnesium from the rock; expect visible limescale on taps, kettles and in boilers; a softener or scale inhibitor is worth considering, especially for hot-water systems.
UK suppliers report mg/L CaCO₃ and often Clark degrees (1 °Clark = 14.25 mg/L).
Water data
| Total hardness | 257 mg/L |
|---|---|
| Utility | Yorkshire Water |
How Rawmarsh compares
- Tap water in Rawmarsh is 39 % harder than the median of the 471 cities we track in the United Kingdom (185 mg/L).
- By hardness it ranks 185 of 471 in the United Kingdom (1 = hardest); 60 % of these cities have softer water.
- In Rotherham it is number 3 of 9 cities; the regional median is 242 mg/L.
- Nearest city with clearly softer water: Treeton, 8 km away (116 mg/L).
- Nearest city with clearly harder water: Hessle, 67 km away (327 mg/L).
Ranking of the hardest and softest water in the United Kingdom →
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 Rawmarsh
| Brand | Setting for this water |
|---|---|
| Bosch | H04 |
| Miele | 14 °dH |
| AEG / Electrolux | 3 |
| Beko | 4th |
| Hoover | S2 |
| LG | H3 |
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 Rawmarsh water hard or soft?
It is very hard: 257 mg/L as CaCO₃ (15 gpg, 14.4 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Rawmarsh 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 Rawmarsh water?
15 gpg, equal to 14.4 °dH, 25.7 °fH or 257 mg/L calcium carbonate.
What dishwasher salt setting should I use in Rawmarsh?
For 257 mg/L (14.4 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Rawmarsh?
Yes, unless you are only passing through: scale damages appliances within a few years.
Source
Source: Yorkshire Water — domestic drinking water quality (Stream open data, CC BY) (2026-08). Method: own measurement. Yorkshire Water — domestic drinking water quality (Stream open data, CC BY) · Outdated figure? Tell us