Water hardness in Donzdorf
19 °dH very hard
Tap water in Donzdorf is very hard: 19 °dH (339 mg/L · 19.8 gpg · 33.9 °fH).
Source: Stadtwerke Donzdorf - Trinkwasser-Prüfbericht Hochbehälter Reichenbach 2025 (Probeneingang 04.11.2025) (2025-11) · data checked 2026-11-03
The figure of 339.2 mg/L CaCO₃ (19.0 °dH) comes from the test report for the Hochbehälter Reichenbach reservoir outlet, sampled on 04.11.2025. The report does not state which share of Donzdorf this reservoir supplies, so the value may not apply to every street. The laboratory calculated the total hardness from calcium and magnesium.
German law (WRMG) uses 3 bands: soft < 8.4 °dH, medium 8.4–14 °dH, hard > 14 °dH.
Water data
| Total hardness | 19 °dH |
|---|---|
| Utility | Stadt Donzdorf, Wasserversorgung (Stadtwerke Donzdorf) |
How Donzdorf compares
- Tap water in Donzdorf is 65 % harder than the median of the 809 cities we track in Germany (11.5 °dH).
- By hardness it ranks 104 of 809 in Germany (1 = hardest); 87 % of these cities have softer water.
- Nearest city with clearly softer water: Göppingen, 10 km away (14.3 °dH).
- Nearest city with clearly harder water: Vaihingen an der Enz, 66 km away (28 °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 Donzdorf
| Brand | Setting for this water |
|---|---|
| Bosch | H05 |
| Miele | 19 °dH |
| AEG / Electrolux | 5 |
| 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 Donzdorf water hard or soft?
It is very hard: 339 mg/L as CaCO₃ (19.8 gpg, 19 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Donzdorf 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 Donzdorf water?
19.8 gpg, equal to 19 °dH, 33.9 °fH or 339 mg/L calcium carbonate.
What dishwasher salt setting should I use in Donzdorf?
For 339 mg/L (19 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Donzdorf?
Yes, unless you are only passing through: scale damages appliances within a few years.
Source
Source: Stadtwerke Donzdorf - Trinkwasser-Prüfbericht Hochbehälter Reichenbach 2025 (Probeneingang 04.11.2025) (2025-11). Method: figure published by the water supplier. Stadtwerke Donzdorf - Trinkwasser-Prüfbericht Hochbehälter Reichenbach 2025 (Probeneingang 04.11.2025) · Outdated figure? Tell us