Water hardness in Jona
33 °fH very hard
Tap water in Jona is very hard: 33 °fH (330 mg/L · 19.3 gpg · 18.5 °dH).
Source: Genossenschaft Wasserversorgung Rapperswil-Jona (via SVGW trinkwasser.ch) (2025) · data checked 2026-11-14
Range across supply zones: 130–350 mg/L.
Jona is served by the Genossenschaft Wasserversorgung Rapperswil-Jona (WVRJ). Its 2025 entry on trinkwasser.ch lists a range of 130 to 350 mg/L CaCO₃, and the 330 mg/L used here is near the top, very hard. The source does not explain the spread, so we cannot say which areas get which value. Ask the utility which one applies to your address.
In der Schweiz wird meist in °fH angegeben (1 °fH = 0,56 °dH).
Water data
| Total hardness | 33 °fH |
|---|---|
| Utility | Genossenschaft Wasserversorgung Rapperswil-Jona (WVRJ) |
How Jona compares
- Tap water in Jona is 23 % harder than the median of the 650 cities we track in Switzerland (26.7 °fH).
- By hardness it ranks 146 of 650 in Switzerland (1 = hardest); 77 % of these cities have softer water.
- In SG it is number 11 of 51 cities; the regional median is 25.3 °fH.
- Nearest city with clearly softer water: Altendorf, 5 km away (24 °fH).
- Nearest city with clearly harder water: Unterlunkhofen, 36 km away (41.3 °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 Jona
| Brand | Setting for this water |
|---|---|
| Bosch | H05 |
| Miele | 18 °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 Jona water hard or soft?
It is very hard: 330 mg/L as CaCO₃ (19.3 gpg, 18.5 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in 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 Jona water?
19.3 gpg, equal to 18.5 °dH, 33 °fH or 330 mg/L calcium carbonate.
What dishwasher salt setting should I use in Jona?
For 330 mg/L (18.5 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in 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