Water hardness in Blois
16.2 °fH hard
Tap water in Blois is hard: 16.2 °fH (162 mg/L · 9.5 gpg · 9.1 °dH).
Source: Ministère de la Santé (ARS), contrôle sanitaire SISE-Eaux, commune 41018 (2026-07) · data checked 2026-10-19
Around Blois, drinking water is drawn from aquifers of the Loire and the Beauce limestone. It measures 162.0 mg/L CaCO₃, a moderate to high hardness. Regular water-heater maintenance is advisable.
TH en °fH : douce < 15, moyennement dure 15–25, dure 25–35, très dure > 35 °fH (classes usuelles ARS).
Water data
| Total hardness | 16.2 °fH |
|---|---|
| Utility | Ca Agglopolys (Aep) |
How Blois compares
- Tap water in Blois is 32 % softer than the median of the 33641 cities we track in France (23.9 °fH).
- By hardness it ranks 23301 of 33641 in France (1 = hardest); 30 % of these cities have softer water.
- In Loir-et-Cher it is number 188 of 267 cities; the regional median is 20.6 °fH.
- Nearest city with clearly softer water: Chailles, 6 km away (1.2 °fH).
- Nearest city with clearly harder water: La Chaussée-Saint-Victor, 4 km away (20.8 °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 Blois
| Brand | Setting for this water |
|---|---|
| Bosch | H02 |
| Miele | 9 °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 Blois water hard or soft?
It is hard: 162 mg/L as CaCO₃ (9.5 gpg, 9.1 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Blois 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 Blois water?
9.5 gpg, equal to 9.1 °dH, 16.2 °fH or 162 mg/L calcium carbonate.
What dishwasher salt setting should I use in Blois?
For 162 mg/L (9.1 °dH) check your manufacturer's table: level 4–5.
Do I need a water softener in Blois?
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 41018 (2026-07). Method: own measurement. Ministère de la Santé (ARS), contrôle sanitaire SISE-Eaux, commune 41018 · Outdated figure? Tell us