Water hardness in Nantes
14.4 °fH hard
Tap water in Nantes is hard: 14.4 °fH (144 mg/L · 8.4 gpg · 8.1 °dH).
Source: Ministère de la Santé (ARS), contrôle sanitaire SISE-Eaux, commune 44109 (2026-08) · data checked 2026-10-19
Nantes Métropole takes most of its water from the Loire at Mauves-sur-Loire, upstream of the city, and treats it at the La Roche plant. The river drains a basin of crystalline and sedimentary rock, giving moderately hard water at 144.0 mg/L CaCO₃. Regular water-heater maintenance limits scale buildup.
TH en °fH : douce < 15, moyennement dure 15–25, dure 25–35, très dure > 35 °fH (classes usuelles ARS).
Water data
| Total hardness | 14.4 °fH |
|---|---|
| Utility | Sca Veolia Eau-Ceo - S. Nt Metro |
How Nantes compares
- Tap water in Nantes is 40 % softer than the median of the 33641 cities we track in France (23.9 °fH).
- By hardness it ranks 25091 of 33641 in France (1 = hardest); 25 % of these cities have softer water.
- In Loire-Atlantique it is number 152 of 169 cities; the regional median is 15.4 °fH.
- Nearest city with clearly softer water: Arzal, 70 km away (10.2 °fH).
- Nearest city with clearly harder water: La Chapelle-sur-Erdre, 9 km away (18.7 °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 Nantes
| Brand | Setting for this water |
|---|---|
| Bosch | H01 |
| Miele | 8 °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 Nantes water hard or soft?
It is hard: 144 mg/L as CaCO₃ (8.4 gpg, 8.1 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Nantes 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 Nantes water?
8.4 gpg, equal to 8.1 °dH, 14.4 °fH or 144 mg/L calcium carbonate.
What dishwasher salt setting should I use in Nantes?
For 144 mg/L (8.1 °dH) check your manufacturer's table: level 4–5.
Do I need a water softener in Nantes?
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 44109 (2026-08). Method: own measurement. Ministère de la Santé (ARS), contrôle sanitaire SISE-Eaux, commune 44109 · Outdated figure? Tell us