Water hardness in Firminy
9.1 °fH moderately hard
Tap water in Firminy is moderately hard: 9.1 °fH (91 mg/L · 5.3 gpg · 5.1 °dH).
Source: Ministère de la Santé (ARS), contrôle sanitaire SISE-Eaux, commune 42095 (2026-08) · data checked 2026-10-19
Range across supply zones: 86–95 mg/L.
Firminy is served by Saint-Étienne Métropole and Veolia. Water for the Saint-Étienne area comes largely from the Lavalette dam on the Lignon du Velay (according to regional press), on volcanic and granitic ground: 91 mg/L CaCO₃, ranging from 86 to 95 mg/L. The water is fairly soft.
TH en °fH : douce < 15, moyennement dure 15–25, dure 25–35, très dure > 35 °fH (classes usuelles ARS).
Water data
| Total hardness | 9.1 °fH |
|---|---|
| Utility | Saint-Etienne Métropole; Veolia Eau Generale Des Eaux |
How Firminy compares
- Tap water in Firminy is 62 % softer than the median of the 33641 cities we track in France (23.9 °fH).
- By hardness it ranks 29721 of 33641 in France (1 = hardest); 11 % of these cities have softer water.
- In Loire it is number 139 of 258 cities; the regional median is 9.6 °fH.
- Nearest city with clearly softer water: Chambles, 7 km away (6.9 °fH).
- Nearest city with clearly harder water: Rivas, 22 km away (21.7 °fH).
Ranking of the hardest and softest water in France →
What it means at home
- Visible kettle scale every few weeks; vinegar or citric acid is enough.
- Water heater and washing machine: some long-term scale; a scale inhibitor slows it.
- Dishwasher: medium salt setting.
- Softener optional; pays off mainly with a gas boiler or tankless heater.
How much salt will you use for softening?
Optional. A scale inhibitor or a small softener protects the heater; soap savings are modest.
Descale a coffee machine or kettle about every 3 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Firminy
| Brand | Setting for this water |
|---|---|
| Bosch | H00 |
| Miele | 5 °dH |
| AEG / Electrolux | 2 |
| Beko | 2nd |
| Hoover | S1 |
| LG | H1 |
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 Firminy water hard or soft?
It is moderately hard: 91 mg/L as CaCO₃ (5.3 gpg, 5.1 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Firminy 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 Firminy water?
5.3 gpg, equal to 5.1 °dH, 9.1 °fH or 91 mg/L calcium carbonate.
What dishwasher salt setting should I use in Firminy?
For 91 mg/L (5.1 °dH) check your manufacturer's table: level 2–3.
Do I need a water softener in Firminy?
Not essential; a scale inhibitor protects the heater cheaply.
Source
Source: Ministère de la Santé (ARS), contrôle sanitaire SISE-Eaux, commune 42095 (2026-08). Method: own measurement. Ministère de la Santé (ARS), contrôle sanitaire SISE-Eaux, commune 42095 · Outdated figure? Tell us