Water hardness in Idstein
11.6 °dH very hard
Tap water in Idstein is very hard: 11.6 °dH (207 mg/L · 12.1 gpg · 20.7 °fH).
Source: Stadtwerke Idstein - Trinkwasserversorgung Informationen zur Wasserqualität 2026 (2026) · data checked 2026-10-24
Range across supply zones: 91–320 mg/L.
13 supply zones — hardness varies by neighbourhood; the figure above is the median.
Hardness by district / supply zone
| °dH | mg/L | ||
|---|---|---|---|
| Dasbach und Lenzhahn | 7 | 125 | hard |
| Ehrenbach | 9.7 | 173 | hard |
| Eschenhahn | 8.4 | 150 | hard |
| Heftrich | 11.6 | 207 | very hard |
| Idstein-Kern - Hochzone I | 17.9 | 320 | very hard |
| Idstein-Kern - Hochzone II | 16.2 | 289 | very hard |
| Idstein-Kern - Mittelzone | 14.4 | 257 | very hard |
| Idstein-Kern - Tiefzone | 16.6 | 296 | very hard |
| Kröftel | 5.8 | 104 | moderately hard |
| Nieder - Oberrod | 5.1 | 91 | moderately hard |
| Nieder und Oberauroff | 15 | 268 | very hard |
| Walsdorf | 10.7 | 191 | very hard |
| Wörsdorf | 15.2 | 271 | very hard |
Stadtwerke Idstein publishes a 2026 water-quality report for the town and its districts, with 13 supply zones. Values run from 91.0 mg/L CaCO₃ in Nieder- and Oberrod to 319.5 mg/L in the Idstein-Kern Hochzone I, and the town figure of 207.1 mg/L is the median of the zones. Which zone you live in matters more than the town average, so find your district in the utility's table. Expect heavy limescale in the town centre and noticeably less in the softer outer districts.
German law (WRMG) uses 3 bands: soft < 8.4 °dH, medium 8.4–14 °dH, hard > 14 °dH.
Water data
| Total hardness | 11.6 °dH |
|---|---|
| Utility | Stadtwerke Idstein - Eigenbetrieb der Stadt Idstein |
How Idstein compares
- Tap water in Idstein is close to the median of the 809 cities we track in Germany (11.5 °dH).
- By hardness it ranks 399 of 809 in Germany (1 = hardest); 51 % of these cities have softer water.
- In Hessen it is number 34 of 73 cities; the regional median is 10.7 °dH.
- Nearest city with clearly softer water: Niedernhausen, 6 km away (5.2 °dH).
- Nearest city with clearly harder water: Bad Soden am Taunus, 18 km away (16.4 °dH).
Ranking of the hardest and softest water in Germany →
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 Idstein
| Brand | Setting for this water |
|---|---|
| Bosch | H03 |
| Miele | 12 °dH |
| AEG / Electrolux | 3 |
| 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 Idstein water hard or soft?
It is very hard: 207 mg/L as CaCO₃ (12.1 gpg, 11.6 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Idstein safe to drink?
Hardness is not a health issue; it is about limescale, taste and appliances. Mains water must meet national drinking-water standards. German law (WRMG) uses 3 bands: soft < 8.4 °dH, medium 8.4–14 °dH, hard > 14 °dH.
How many grains per gallon is Idstein water?
12.1 gpg, equal to 11.6 °dH, 20.7 °fH or 207 mg/L calcium carbonate.
What dishwasher salt setting should I use in Idstein?
For 207 mg/L (11.6 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Idstein?
Yes, unless you are only passing through: scale damages appliances within a few years.
Source
Source: Stadtwerke Idstein - Trinkwasserversorgung Informationen zur Wasserqualität 2026 (2026). Method: figure published by the water supplier. Stadtwerke Idstein - Trinkwasserversorgung Informationen zur Wasserqualität 2026 · Outdated figure? Tell us