Water hardness in Harnes
40 °fH very hard
Tap water in Harnes is very hard: 40 °fH (400 mg/L · 23.4 gpg · 22.4 °dH).
Source: Ministère de la Santé (ARS), contrôle sanitaire SISE-Eaux, commune 62413 (2026-08) · data checked 2026-10-19
Range across supply zones: 360–440 mg/L.
Harnes (Pas-de-Calais) is served by Veolia Artois Douaisis. The median is 400 mg/L CaCO₃, with August 2026 measurements from 360 to 440 mg/L. The water is very hard across the whole published range.
TH en °fH : douce < 15, moyennement dure 15–25, dure 25–35, très dure > 35 °fH (classes usuelles ARS).
Water data
| Total hardness | 40 °fH |
|---|---|
| Utility | Veolia Artois Douaisis |
How Harnes compares
- Tap water in Harnes is 67 % harder than the median of the 33641 cities we track in France (23.9 °fH).
- By hardness it ranks 830 of 33641 in France (1 = hardest); 97 % of these cities have softer water.
- In Pas-de-Calais it is number 31 of 880 cities; the regional median is 32.9 °fH.
- Nearest city with clearly softer water: Vimy, 10 km away (31.3 °fH).
- Nearest city with clearly harder water: Remigny, 85 km away (51.6 °fH).
Ranking of the hardest and softest water in France →
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 Harnes
| Brand | Setting for this water |
|---|---|
| Bosch | H06 |
| Miele | 22 °dH |
| AEG / Electrolux | 5 |
| Beko | 6th |
| Hoover | S3 |
| LG | H4 |
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 Harnes water hard or soft?
It is very hard: 400 mg/L as CaCO₃ (23.4 gpg, 22.4 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Harnes safe to drink?
Hardness is not a health issue; it is about limescale, taste and appliances. Mains water must meet national drinking-water standards. TH en °fH : douce < 15, moyennement dure 15–25, dure 25–35, très dure > 35 °fH (classes usuelles ARS).
How many grains per gallon is Harnes water?
23.4 gpg, equal to 22.4 °dH, 40 °fH or 400 mg/L calcium carbonate.
What dishwasher salt setting should I use in Harnes?
For 400 mg/L (22.4 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Harnes?
Yes, unless you are only passing through: scale damages appliances within a few years.
Source
Source: Ministère de la Santé (ARS), contrôle sanitaire SISE-Eaux, commune 62413 (2026-08). Method: own measurement. Ministère de la Santé (ARS), contrôle sanitaire SISE-Eaux, commune 62413 · Outdated figure? Tell us