Water hardness in Voiron
22.9 °fH very hard
Tap water in Voiron is very hard: 22.9 °fH (229 mg/L · 13.4 gpg · 12.8 °dH).
Source: Ministère de la Santé (ARS), contrôle sanitaire SISE-Eaux, commune 38563 (2026-07) · data checked 2026-10-19
Range across supply zones: 209–266 mg/L.
Voiron is supplied by the Pays Voironnais agglomeration, west of the Alps. Local water passes through limestone terrain around the Chartreuse massif and the plain, which gives very hard water: 229 mg/L CaCO₃, with readings between 209 and 266 mg/L. Descaling kettles and shower screens is a routine task here.
TH en °fH : douce < 15, moyennement dure 15–25, dure 25–35, très dure > 35 °fH (classes usuelles ARS).
Water data
| Total hardness | 22.9 °fH |
|---|---|
| Utility | Ca Du Pays Voironnais |
How Voiron compares
- Tap water in Voiron is close to the median of the 33641 cities we track in France (23.9 °fH).
- By hardness it ranks 17917 of 33641 in France (1 = hardest); 47 % of these cities have softer water.
- In Isère it is number 293 of 502 cities; the regional median is 25.1 °fH.
- Nearest city with clearly softer water: La Sure en Chartreuse, 6 km away (15.1 °fH).
- Nearest city with clearly harder water: La Murette, 4 km away (30.6 °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 Voiron
| Brand | Setting for this water |
|---|---|
| Bosch | H04 |
| Miele | 13 °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 Voiron water hard or soft?
It is very hard: 229 mg/L as CaCO₃ (13.4 gpg, 12.8 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Voiron 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 Voiron water?
13.4 gpg, equal to 12.8 °dH, 22.9 °fH or 229 mg/L calcium carbonate.
What dishwasher salt setting should I use in Voiron?
For 229 mg/L (12.8 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Voiron?
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 38563 (2026-07). Method: own measurement. Ministère de la Santé (ARS), contrôle sanitaire SISE-Eaux, commune 38563 · Outdated figure? Tell us