Water hardness in Karlsruhe
18.4 °dH very hard
Tap water in Karlsruhe is very hard: 18.4 °dH (329 mg/L · 19.2 gpg · 32.9 °fH).
Source: Stadtwerke Karlsruhe: Trinkwasser Jahresmittelwerte 2025 (2025) · data checked 2026-10-19
Range across supply zones: 327–332 mg/L.
2 supply zones — hardness varies by neighbourhood; the figure above is the median.
Hardness by district / supply zone
| °dH | mg/L | ||
|---|---|---|---|
| citywide (Stadtwerke Karlsruhe works) | 18.3 | 327 | very hard |
| Höhenstadtteile (Grünwettersbach, Palmbach, Stupferich) | 18.6 | 332 | very hard |
Stadtwerke Karlsruhe publishes 2025 annual means for the main network and for the hill districts of Grünwettersbach, Palmbach and Stupferich. The median is 329.3 mg/L CaCO₃ and the two zones differ by only a few mg/L (326.7 to 332.0). Hardness is therefore similar across the city and is in the hard range under the WRMG.
German law (WRMG) uses 3 bands: soft < 8.4 °dH, medium 8.4–14 °dH, hard > 14 °dH.
Water data
| Total hardness | 18.4 °dH |
|---|---|
| Utility | Stadtwerke Karlsruhe GmbH |
How Karlsruhe compares
- Tap water in Karlsruhe is 60 % harder than the median of the 809 cities we track in Germany (11.5 °dH).
- By hardness it ranks 130 of 809 in Germany (1 = hardest); 84 % of these cities have softer water.
- In Baden-Württemberg it is number 25 of 146 cities; the regional median is 12.8 °dH.
- Nearest city with clearly softer water: Hagenbach, 11 km away (14.5 °dH).
- Nearest city with clearly harder water: Nußloch, 40 km away (31.6 °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 Karlsruhe
| 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 Karlsruhe water hard or soft?
It is very hard: 329 mg/L as CaCO₃ (19.2 gpg, 18.4 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Karlsruhe 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 Karlsruhe water?
19.2 gpg, equal to 18.4 °dH, 32.9 °fH or 329 mg/L calcium carbonate.
What dishwasher salt setting should I use in Karlsruhe?
For 329 mg/L (18.4 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Karlsruhe?
Yes, unless you are only passing through: scale damages appliances within a few years.
Source
Source: Stadtwerke Karlsruhe: Trinkwasser Jahresmittelwerte 2025 (2025). Method: figure published by the water supplier. Stadtwerke Karlsruhe: Trinkwasser Jahresmittelwerte 2025 · Outdated figure? Tell us