Water hardness in Dortmund
7.7 °dH hard
Tap water in Dortmund is hard: 7.7 °dH (137 mg/L · 8 gpg · 13.7 °fH).
Source: DEW21, Unser Wasser für Dortmund – Produkteigenschaften (2026) · data checked 2026-10-22
DEW21 lists a single hardness figure of 137.4 mg/L CaCO₃ for its Dortmund water in its product data sheet, which puts the city in the hard band. The utility page does not break the figure down by district, so treat it as a city-wide value. Neighbouring towns vary widely, from Hagen at 128.5 mg/L to Waltrop at 201.7 mg/L, so a figure from another town is not a safe substitute.
German law (WRMG) uses 3 bands: soft < 8.4 °dH, medium 8.4–14 °dH, hard > 14 °dH.
Water data
| Total hardness | 7.7 °dH |
|---|---|
| Utility | DEW21 (Wasserwerke Westfalen) |
How Dortmund compares
- Tap water in Dortmund is 33 % softer than the median of the 809 cities we track in Germany (11.5 °dH).
- By hardness it ranks 587 of 809 in Germany (1 = hardest); 27 % of these cities have softer water.
- In Nordrhein-Westfalen it is number 117 of 153 cities; the regional median is 11.3 °dH.
- Nearest city with clearly softer water: Sprockhövel, 33 km away (3.5 °dH).
- Nearest city with clearly harder water: Waltrop, 13 km away (11.3 °dH).
Ranking of the hardest and softest water in Germany →
What it means at home
- Fast scale on taps, shower screens and kettle; white spots on glassware.
- Water heater: efficiency loss and element failures within years if unprotected.
- Dry skin and dull hair after showering are common.
- Softener recommended; jug or reverse osmosis for drinking.
How much salt will you use for softening?
Recommended, especially with a heater or boiler: scale cuts efficiency and shortens its life.
Descale a coffee machine or kettle about every 2 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Dortmund
| Brand | Setting for this water |
|---|---|
| Bosch | H01 |
| Miele | 8 °dH |
| AEG / Electrolux | 2 |
| Beko | 2nd |
| Hoover | S1 |
| 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 Dortmund water hard or soft?
It is hard: 137 mg/L as CaCO₃ (8 gpg, 7.7 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Dortmund 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 Dortmund water?
8 gpg, equal to 7.7 °dH, 13.7 °fH or 137 mg/L calcium carbonate.
What dishwasher salt setting should I use in Dortmund?
For 137 mg/L (7.7 °dH) check your manufacturer's table: level 4–5.
Do I need a water softener in Dortmund?
Recommended if you have a water heater, boiler or tankless unit: it saves repairs and detergent.
Source
Source: DEW21, Unser Wasser für Dortmund – Produkteigenschaften (2026). Method: figure published by the water supplier. DEW21, Unser Wasser für Dortmund – Produkteigenschaften · Outdated figure? Tell us