Water hardness in Persan
37.9 °fH very hard
Tap water in Persan is very hard: 37.9 °fH (379 mg/L · 22.1 gpg · 21.2 °dH).
Source: Ministère de la Santé (ARS), contrôle sanitaire SISE-Eaux, commune 95487 (2026-04) · data checked 2026-10-19
Persan (Val-d'Oise) is supplied by Suez Eau France, Haut De France. The ARS health control (SISE-Eaux, April 2026) records 379 mg/L CaCO₃, one of the harder values in this batch. No range is published.
TH en °fH : douce < 15, moyennement dure 15–25, dure 25–35, très dure > 35 °fH (classes usuelles ARS).
Water data
| Total hardness | 37.9 °fH |
|---|---|
| Utility | Suez Eau France - Haut De France |
How Persan compares
- Tap water in Persan is 59 % harder than the median of the 33641 cities we track in France (23.9 °fH).
- By hardness it ranks 1445 of 33641 in France (1 = hardest); 96 % of these cities have softer water.
- In Val-d'Oise it is number 33 of 149 cities; the regional median is 30.6 °fH.
- Nearest city with clearly softer water: Ronquerolles, 4 km away (22 °fH).
- Nearest city with clearly harder water: Barbery, 30 km away (48.5 °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 Persan
| Brand | Setting for this water |
|---|---|
| Bosch | H06 |
| Miele | 21 °dH |
| AEG / Electrolux | 5 |
| Beko | 6th |
| Hoover | S3 |
| LG | H4 |
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 Persan water hard or soft?
It is very hard: 379 mg/L as CaCO₃ (22.1 gpg, 21.2 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Persan 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 Persan water?
22.1 gpg, equal to 21.2 °dH, 37.9 °fH or 379 mg/L calcium carbonate.
What dishwasher salt setting should I use in Persan?
For 379 mg/L (21.2 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Persan?
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 95487 (2026-04). Method: own measurement. Ministère de la Santé (ARS), contrôle sanitaire SISE-Eaux, commune 95487 · Outdated figure? Tell us