Water hardness in Sainte-Geneviève-des-Bois (Essonne)
24.4 °fH very hard
Tap water in Sainte-Geneviève-des-Bois (Essonne) is very hard: 24.4 °fH (244 mg/L · 14.3 gpg · 13.7 °dH).
Source: Ministère de la Santé (ARS), contrôle sanitaire SISE-Eaux, commune 91549 (2026-08) · data checked 2026-10-19
In the Essonne, in Sainte-Geneviève-des-Bois, drinking water comes mostly from the Seine and groundwater, treated at plants. Paris Basin limestone gives 244.0 mg/L CaCO₃. Regular descaling is advisable.
TH en °fH : douce < 15, moyennement dure 15–25, dure 25–35, très dure > 35 °fH (classes usuelles ARS).
Water data
| Total hardness | 24.4 °fH |
|---|---|
| Utility | Regie Publ. Eau Coeur D'Essonne Agg |
How Sainte-Geneviève-des-Bois (Essonne) compares
- Tap water in Sainte-Geneviève-des-Bois (Essonne) is close to the median of the 33641 cities we track in France (23.9 °fH).
- By hardness it ranks 16257 of 33641 in France (1 = hardest); 51 % of these cities have softer water.
- In Essonne it is number 133 of 194 cities; the regional median is 25.9 °fH.
- Nearest city with clearly softer water: Villebon-sur-Yvette, 10 km away (19 °fH).
- Nearest city with clearly harder water: Bruyères-le-Châtel, 11 km away (38.3 °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 Sainte-Geneviève-des-Bois
| Brand | Setting for this water |
|---|---|
| Bosch | H04 |
| Miele | 14 °dH |
| AEG / Electrolux | 3 |
| Beko | 4th |
| Hoover | S2 |
| LG | H2 |
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 Sainte-Geneviève-des-Bois (Essonne) water hard or soft?
It is very hard: 244 mg/L as CaCO₃ (14.3 gpg, 13.7 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Sainte-Geneviève-des-Bois (Essonne) 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 Sainte-Geneviève-des-Bois (Essonne) water?
14.3 gpg, equal to 13.7 °dH, 24.4 °fH or 244 mg/L calcium carbonate.
What dishwasher salt setting should I use in Sainte-Geneviève-des-Bois (Essonne)?
For 244 mg/L (13.7 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Sainte-Geneviève-des-Bois (Essonne)?
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 91549 (2026-08). Method: own measurement. Ministère de la Santé (ARS), contrôle sanitaire SISE-Eaux, commune 91549 · Outdated figure? Tell us