Water hardness in Saint-Martin-d'Hères
17.3 °fH hard
Tap water in Saint-Martin-d'Hères is hard: 17.3 °fH (173 mg/L · 10.1 gpg · 9.7 °dH).
Source: Ministère de la Santé (ARS), contrôle sanitaire SISE-Eaux, commune 38421 (2026-08) · data checked 2026-10-19
Range across supply zones: 161–186 mg/L.
Saint-Martin-d'Hères is served by the Grenoble Alpes Métropole utility, whose water comes largely from the Drac aquifer, captured at Rochefort, and from hillside springs. The Alpine rock of this basin gives 173.0 mg/L CaCO₃, with values from 161.0 to 186.0 mg/L depending on the zone. Scale stays moderate.
TH en °fH : douce < 15, moyennement dure 15–25, dure 25–35, très dure > 35 °fH (classes usuelles ARS).
Water data
| Total hardness | 17.3 °fH |
|---|---|
| Utility | Grenoble Alpes Metropole |
How Saint-Martin-d'Hères compares
- Tap water in Saint-Martin-d'Hères is 28 % softer than the median of the 33641 cities we track in France (23.9 °fH).
- By hardness it ranks 22382 of 33641 in France (1 = hardest); 33 % of these cities have softer water.
- In Isère it is number 381 of 502 cities; the regional median is 25.1 °fH.
- Nearest city with clearly softer water: Poisat, 1 km away (11.9 °fH).
- Nearest city with clearly harder water: Seyssins, 7 km away (24.6 °fH).
Ranking of the hardest and softest water in France →
What it means at home
- Fast scale on taps, shower screens and kettle; white spots on glassware.
- Water heater: efficiency loss and element failures within years if unprotected.
- Dry skin and dull hair after showering are common.
- Softener recommended; jug or reverse osmosis for drinking.
How much salt will you use for softening?
Recommended, especially with a heater or boiler: scale cuts efficiency and shortens its life.
Descale a coffee machine or kettle about every 2 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Saint-Martin-d'Hères
| Brand | Setting for this water |
|---|---|
| Bosch | H02 |
| Miele | 10 °dH |
| AEG / Electrolux | 2 |
| Beko | 3rd |
| Hoover | S1 |
| 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 Saint-Martin-d'Hères water hard or soft?
It is hard: 173 mg/L as CaCO₃ (10.1 gpg, 9.7 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Saint-Martin-d'Hères 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 Saint-Martin-d'Hères water?
10.1 gpg, equal to 9.7 °dH, 17.3 °fH or 173 mg/L calcium carbonate.
What dishwasher salt setting should I use in Saint-Martin-d'Hères?
For 173 mg/L (9.7 °dH) check your manufacturer's table: level 4–5.
Do I need a water softener in Saint-Martin-d'Hères?
Recommended if you have a water heater, boiler or tankless unit: it saves repairs and detergent.
Source
Source: Ministère de la Santé (ARS), contrôle sanitaire SISE-Eaux, commune 38421 (2026-08). Method: own measurement. Ministère de la Santé (ARS), contrôle sanitaire SISE-Eaux, commune 38421 · Outdated figure? Tell us