Water hardness in Denain
45.4 °fH very hard
Tap water in Denain is very hard: 45.4 °fH (454 mg/L · 26.5 gpg · 25.4 °dH).
Source: Ministère de la Santé (ARS), contrôle sanitaire SISE-Eaux, commune 59172 (2026-08) · data checked 2026-10-19
Denain is supplied by Siden-Sian (Noréade) in the Nord, where water largely comes from the chalk aquifer. Chalk dissolves limestone readily: 454 mg/L CaCO₃, one of the highest values in the country. A softener is often considered in the area.
TH en °fH : douce < 15, moyennement dure 15–25, dure 25–35, très dure > 35 °fH (classes usuelles ARS).
Water data
| Total hardness | 45.4 °fH |
|---|---|
| Utility | Siden-Sian Noreade Le Quesnoy |
How Denain compares
- Tap water in Denain is 90 % harder than the median of the 33641 cities we track in France (23.9 °fH).
- By hardness it ranks 201 of 33641 in France (1 = hardest); 99 % of these cities have softer water.
- In Nord it is number 41 of 634 cities; the regional median is 35.8 °fH.
- Nearest city with clearly softer water: Abscon, 7 km away (35.5 °fH).
- Nearest city with clearly harder water: Rozières-sur-Crise, 111 km away (58 °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 Denain
| Brand | Setting for this water |
|---|---|
| Bosch | H06 |
| Miele | 25 °dH |
| AEG / Electrolux | 6 |
| 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 Denain water hard or soft?
It is very hard: 454 mg/L as CaCO₃ (26.5 gpg, 25.4 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Denain 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 Denain water?
26.5 gpg, equal to 25.4 °dH, 45.4 °fH or 454 mg/L calcium carbonate.
What dishwasher salt setting should I use in Denain?
For 454 mg/L (25.4 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Denain?
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 59172 (2026-08). Method: own measurement. Ministère de la Santé (ARS), contrôle sanitaire SISE-Eaux, commune 59172 · Outdated figure? Tell us