Water hardness in Geneva
18.2 °fH very hard
Tap water in Geneva is very hard: 18.2 °fH (182 mg/L · 10.6 gpg · 10.2 °dH).
Source: SIG, Quel bilan pour mon eau potable en 2024 ? (brochure, April 2025) (2024) · data checked 2026-10-21
Range across supply zones: 134–225 mg/L.
4 supply zones — hardness varies by neighbourhood; the figure above is the median.
Hardness by district / supply zone
| °fH | mg/L | ||
|---|---|---|---|
| Zone 1 Eau du lac | 13.4 | 135 | hard |
| Zone 2 Eau du lac et nappe de l Allondon | 17.9 | 180 | hard |
| Zone 3 Eau du lac et nappe du Genevois | 18.5 | 185 | very hard |
| Zone 4 Nappe du Genevois | 20.4 | 204 | very hard |
Geneva is supplied mostly with water from Lake Geneva, supplemented by the Genevois aquifer, which is recharged mainly by the Arve. Services industriels de Genève (SIG) reports a hardness of 182.2 mg/L CaCO₃ across 4 supply zones, with values from 134.0 to 225.0 mg/L depending on the address. Scale forms quickly on heating elements and fittings, so a softener or strict descaling routine is worth considering.
In der Schweiz wird meist in °fH angegeben (1 °fH = 0,56 °dH).
Water data
| Total hardness | 18.2 °fH |
|---|---|
| Utility | Services industriels de Genève (SIG) |
How Geneva compares
- Tap water in Geneva is 32 % softer than the median of the 650 cities we track in Switzerland (26.7 °fH).
- By hardness it ranks 525 of 650 in Switzerland (1 = hardest); 19 % of these cities have softer water.
- Nearest city with clearly softer water: Chamoson, 83 km away (13.9 °fH).
- Nearest city with clearly harder water: Eysins, 20 km away (25.2 °fH).
Ranking of the hardest and softest water in Switzerland →
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 Geneva
| Brand | Setting for this water |
|---|---|
| Bosch | H02 |
| Miele | 10 °dH |
| AEG / Electrolux | 2 |
| Beko | 3rd |
| 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 Geneva water hard or soft?
It is very hard: 182 mg/L as CaCO₃ (10.6 gpg, 10.2 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Geneva safe to drink?
Hardness is not a health issue; it is about limescale, taste and appliances. Mains water must meet national drinking-water standards. In der Schweiz wird meist in °fH angegeben (1 °fH = 0,56 °dH).
How many grains per gallon is Geneva water?
10.6 gpg, equal to 10.2 °dH, 18.2 °fH or 182 mg/L calcium carbonate.
What dishwasher salt setting should I use in Geneva?
For 182 mg/L (10.2 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Geneva?
Yes, unless you are only passing through: scale damages appliances within a few years.
Source
Source: SIG, Quel bilan pour mon eau potable en 2024 ? (brochure, April 2025) (2024). Method: computed from supplier's calcium and magnesium. SIG, Quel bilan pour mon eau potable en 2024 ? (brochure, April 2025) · Outdated figure? Tell us