Water hardness in Thalwil
23.5 °fH very hard
Tap water in Thalwil is very hard: 23.5 °fH (235 mg/L · 13.7 gpg · 13.2 °dH).
Source: Gemeinde Thalwil (via SVGW trinkwasser.ch) (2025) · data checked 2026-10-21
Range across supply zones: 202–268 mg/L.
The municipality lies on Lake Zurich, and part of the drinking water in the lakeside communities is treated lake water, the rest groundwater and spring water. Gemeinde Thalwil reports a hardness of 235.0 mg/L CaCO₃, with values from 201.7 to 268.2 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 | 23.5 °fH |
|---|---|
| Utility | Gemeinde Thalwil |
How Thalwil compares
- Tap water in Thalwil is 12 % softer than the median of the 650 cities we track in Switzerland (26.7 °fH).
- By hardness it ranks 419 of 650 in Switzerland (1 = hardest); 35 % of these cities have softer water.
- In ZH it is number 88 of 116 cities; the regional median is 28.4 °fH.
- Nearest city with clearly softer water: Herrliberg, 4 km away (15 °fH).
- Nearest city with clearly harder water: Hausen am Albis, 6 km away (31.3 °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 Thalwil
| Brand | Setting for this water |
|---|---|
| Bosch | H04 |
| Miele | 13 °dH |
| AEG / Electrolux | 3 |
| Beko | 4th |
| 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 Thalwil water hard or soft?
It is very hard: 235 mg/L as CaCO₃ (13.7 gpg, 13.2 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Thalwil 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 Thalwil water?
13.7 gpg, equal to 13.2 °dH, 23.5 °fH or 235 mg/L calcium carbonate.
What dishwasher salt setting should I use in Thalwil?
For 235 mg/L (13.2 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Thalwil?
Yes, unless you are only passing through: scale damages appliances within a few years.
Source
Source: Gemeinde Thalwil (via SVGW trinkwasser.ch) (2025). Method: figure published by the water supplier. Gemeinde Thalwil (via SVGW trinkwasser.ch) · Outdated figure? Tell us