Water hardness in Athis-Mons
25.2 °fH very hard
Tap water in Athis-Mons is very hard: 25.2 °fH (252 mg/L · 14.7 gpg · 14.1 °dH).
Source: Ministère de la Santé (ARS), contrôle sanitaire SISE-Eaux, commune 91027 (2026-08) · data checked 2026-10-19
Range across supply zones: 241–310 mg/L.
In Athis-Mons (Essonne), the reported value is 252 mg/L CaCO₃ (25.2 °f), within a range of 241 to 310 mg/L. That is very hard water. Three suppliers appear in the data: Franciliane, the Régie des eaux de la Seine et de la Bièvre and Veolia Eau Île-de-France. Measurements come from ARS sanitary monitoring, August 2026.
TH en °fH : douce < 15, moyennement dure 15–25, dure 25–35, très dure > 35 °fH (classes usuelles ARS).
Water data
| Total hardness | 25.2 °fH |
|---|---|
| Utility | Franciliane; Regie Des Eaux De La Seine Et De La Bievre; Veolia Eau Ile De France |
How Athis-Mons compares
- Tap water in Athis-Mons is 5 % harder than the median of the 33641 cities we track in France (23.9 °fH).
- By hardness it ranks 15250 of 33641 in France (1 = hardest); 54 % of these cities have softer water.
- In Essonne it is number 112 of 194 cities; the regional median is 25.9 °fH.
- Nearest city with clearly softer water: Villebon-sur-Yvette, 11 km away (19 °fH).
- Nearest city with clearly harder water: Boussy-Saint-Antoine, 11 km away (32.2 °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 Athis-Mons
| Brand | Setting for this water |
|---|---|
| Bosch | H04 |
| Miele | 14 °dH |
| AEG / Electrolux | 3 |
| Beko | 4th |
| Hoover | S2 |
| 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 Athis-Mons water hard or soft?
It is very hard: 252 mg/L as CaCO₃ (14.7 gpg, 14.1 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Athis-Mons 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 Athis-Mons water?
14.7 gpg, equal to 14.1 °dH, 25.2 °fH or 252 mg/L calcium carbonate.
What dishwasher salt setting should I use in Athis-Mons?
For 252 mg/L (14.1 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Athis-Mons?
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 91027 (2026-08). Method: own measurement. Ministère de la Santé (ARS), contrôle sanitaire SISE-Eaux, commune 91027 · Outdated figure? Tell us