Water hardness in Rapperswil-Jona
30.7 °fH very hard
Tap water in Rapperswil-Jona is very hard: 30.7 °fH (307 mg/L · 17.9 gpg · 17.2 °dH).
Source: Genossenschaft Wasserversorgung Rapperswil-Jona (via SVGW trinkwasser.ch) (2025) · data checked 2026-10-21
Range across supply zones: 180–330 mg/L.
In eastern Switzerland, drinking water comes from groundwater, hill springs and in places lake water, depending on the supply area. Genossenschaft Wasserversorgung Rapperswil-Jona reports a hardness of 307.0 mg/L CaCO₃, with values from 180.0 to 330.0 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 | 30.7 °fH |
|---|---|
| Utility | Genossenschaft Wasserversorgung Rapperswil-Jona |
How Rapperswil-Jona compares
- Tap water in Rapperswil-Jona is 15 % harder than the median of the 650 cities we track in Switzerland (26.7 °fH).
- By hardness it ranks 214 of 650 in Switzerland (1 = hardest); 67 % of these cities have softer water.
- In SG it is number 18 of 51 cities; the regional median is 25.3 °fH.
- Nearest city with clearly softer water: Altendorf, 4 km away (24 °fH).
- Nearest city with clearly harder water: Kirchberg, 26 km away (39.3 °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 Rapperswil-Jona
| Brand | Setting for this water |
|---|---|
| Bosch | H05 |
| Miele | 17 °dH |
| AEG / Electrolux | 4 |
| Beko | 5th |
| Hoover | S3 |
| LG | H3 |
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 Rapperswil-Jona water hard or soft?
It is very hard: 307 mg/L as CaCO₃ (17.9 gpg, 17.2 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Rapperswil-Jona 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 Rapperswil-Jona water?
17.9 gpg, equal to 17.2 °dH, 30.7 °fH or 307 mg/L calcium carbonate.
What dishwasher salt setting should I use in Rapperswil-Jona?
For 307 mg/L (17.2 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Rapperswil-Jona?
Yes, unless you are only passing through: scale damages appliances within a few years.
Source
Source: Genossenschaft Wasserversorgung Rapperswil-Jona (via SVGW trinkwasser.ch) (2025). Method: figure published by the water supplier. Genossenschaft Wasserversorgung Rapperswil-Jona (via SVGW trinkwasser.ch) · Outdated figure? Tell us