Water hardness in Boulogne-sur-Mer
36.2 °fH very hard
Tap water in Boulogne-sur-Mer is very hard: 36.2 °fH (362 mg/L · 21.1 gpg · 20.3 °dH).
Source: Ministère de la Santé (ARS), contrôle sanitaire SISE-Eaux, commune 62160 (2026-05) · data checked 2026-10-19
Range across supply zones: 343–380 mg/L.
In the Boulonnais, drinking water is drawn from the chalk aquifer. Chalk gives very hard water: 362.0 mg/L CaCO₃, between 343.0 and 380.0 mg/L. Scale forms quickly, and a softener is often considered.
TH en °fH : douce < 15, moyennement dure 15–25, dure 25–35, très dure > 35 °fH (classes usuelles ARS).
Water data
| Total hardness | 36.2 °fH |
|---|---|
| Utility | Veolia Littoral Audomarois |
How Boulogne-sur-Mer compares
- Tap water in Boulogne-sur-Mer is 51 % harder than the median of the 33641 cities we track in France (23.9 °fH).
- By hardness it ranks 2043 of 33641 in France (1 = hardest); 94 % of these cities have softer water.
- In Pas-de-Calais it is number 121 of 880 cities; the regional median is 32.9 °fH.
- Nearest city with clearly softer water: Condette, 8 km away (28.7 °fH).
- Nearest city with clearly harder water: Haverskerque, 66 km away (45.7 °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 Boulogne-sur-Mer
| Brand | Setting for this water |
|---|---|
| Bosch | H05 |
| Miele | 20 °dH |
| AEG / Electrolux | 5 |
| Beko | 6th |
| 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 Boulogne-sur-Mer water hard or soft?
It is very hard: 362 mg/L as CaCO₃ (21.1 gpg, 20.3 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Boulogne-sur-Mer 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 Boulogne-sur-Mer water?
21.1 gpg, equal to 20.3 °dH, 36.2 °fH or 362 mg/L calcium carbonate.
What dishwasher salt setting should I use in Boulogne-sur-Mer?
For 362 mg/L (20.3 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Boulogne-sur-Mer?
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 62160 (2026-05). Method: own measurement. Ministère de la Santé (ARS), contrôle sanitaire SISE-Eaux, commune 62160 · Outdated figure? Tell us