Water hardness in Ilminster
307 mg/L very hard
Tap water in Ilminster is very hard: 307 mg/L (17.9 gpg · 17.2 °dH · 30.7 °fH).
Source: Wessex Water — domestic drinking water quality (Stream open data, CC BY) (2025-11) · data checked 2026-10-20
Range across supply zones: 115–372 mg/L.
UK suppliers report mg/L CaCO₃ and often Clark degrees (1 °Clark = 14.25 mg/L).
Water data
| Total hardness | 307 mg/L |
|---|---|
| Utility | Wessex Water |
How Ilminster compares
- Tap water in Ilminster is 66 % harder than the median of the 471 cities we track in the United Kingdom (185 mg/L).
- By hardness it ranks 41 of 471 in the United Kingdom (1 = hardest); 91 % of these cities have softer water.
- In South Somerset it is number 2 of 12 cities; the regional median is 234 mg/L.
- Nearest city with clearly softer water: South Petherton, 8 km away (81 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 Ilminster
| Brand | Setting for this water |
|---|---|
| Bosch | H05 |
| Miele | 17 °dH |
| AEG / Electrolux | 4 |
| Beko | 5th |
| Hoover | S3 |
| 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 Ilminster water hard or soft?
It is very hard: 307 mg/L as CaCO₃ (17.9 gpg, 17.2 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Ilminster 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 Ilminster water?
17.9 gpg, equal to 17.2 °dH, 30.7 °fH or 307 mg/L calcium carbonate.
What dishwasher salt setting should I use in Ilminster?
For 307 mg/L (17.2 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Ilminster?
Yes, unless you are only passing through: scale damages appliances within a few years.
Source
Source: Wessex Water — domestic drinking water quality (Stream open data, CC BY) (2025-11). Method: own measurement. Wessex Water — domestic drinking water quality (Stream open data, CC BY) · Outdated figure? Tell us