Water hardness in Düren
6.4 °dH moderately hard
Tap water in Düren is moderately hard: 6.4 °dH (115 mg/L · 6.7 gpg · 11.5 °fH).
Source: Stadtwerke Düren – Wasserhärte nach §9 WRMG, Analysezeitraum Juli 2025 bis Juni 2026 (2026) · data checked 2026-10-23
Range across supply zones: 52–186 mg/L.
4 supply zones — hardness varies by neighbourhood; the figure above is the median.
Hardness by district / supply zone
| °dH | mg/L | ||
|---|---|---|---|
| Derichsweiler (Lieferant WZV Langerwehe) | 7.2 | 129 | hard |
| Wasserbehälter Hemgenberg (Berzbuir, Birgel, Kufferath) | 3.3 | 59 | soft |
| Wasserbehälter Kirmesplatz (Arnoldsweiler, Birkesdorf, Düren-Zentrum, Gürzenich, Hoven, Mariaweiler, Merken, Merzenich, Morschenich-Neu, Rölsdorf) | 8.2 | 146 | hard |
| WB Hemgenberg / WB Kirmesplatz (Krauthausen, Lendersdorf, Niederau) | 5.7 | 102 | moderately hard |
Stadtwerke Düren publishes a hardness list under §9 WRMG for July 2025 to June 2026, split into four supply areas. Values run from 58.9 mg/L CaCO₃ (Hemgenberg reservoir) to 146.4 mg/L (Kirmesplatz reservoir, which includes the town centre). The city figure is 115.1 mg/L. Düren is much softer than Elsdorf (264.2 mg/L) and Kerpen to the east.
German law (WRMG) uses 3 bands: soft < 8.4 °dH, medium 8.4–14 °dH, hard > 14 °dH.
Water data
| Total hardness | 6.4 °dH |
|---|---|
| Utility | Stadtwerke Düren (SWD) |
How Düren compares
- Tap water in Düren is 44 % softer than the median of the 809 cities we track in Germany (11.5 °dH).
- By hardness it ranks 678 of 809 in Germany (1 = hardest); 16 % of these cities have softer water.
- In Nordrhein-Westfalen it is number 133 of 153 cities; the regional median is 11.3 °dH.
- Nearest city with clearly softer water: Leichlingen, 51 km away (4.4 °dH).
- Nearest city with clearly harder water: Elsdorf, 16 km away (14.8 °dH).
Ranking of the hardest and softest water in Germany →
What it means at home
- Visible kettle scale every few weeks; vinegar or citric acid is enough.
- Water heater and washing machine: some long-term scale; a scale inhibitor slows it.
- Dishwasher: medium salt setting.
- Softener optional; pays off mainly with a gas boiler or tankless heater.
How much salt will you use for softening?
Optional. A scale inhibitor or a small softener protects the heater; soap savings are modest.
Descale a coffee machine or kettle about every 3 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Düren
| Brand | Setting for this water |
|---|---|
| Bosch | H00 |
| Miele | 6 °dH |
| AEG / Electrolux | 2 |
| Beko | 2nd |
| Hoover | S1 |
| LG | H1 |
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 Düren water hard or soft?
It is moderately hard: 115 mg/L as CaCO₃ (6.7 gpg, 6.4 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Düren 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 Düren water?
6.7 gpg, equal to 6.4 °dH, 11.5 °fH or 115 mg/L calcium carbonate.
What dishwasher salt setting should I use in Düren?
For 115 mg/L (6.4 °dH) check your manufacturer's table: level 2–3.
Do I need a water softener in Düren?
Not essential; a scale inhibitor protects the heater cheaply.
Source
Source: Stadtwerke Düren – Wasserhärte nach §9 WRMG, Analysezeitraum Juli 2025 bis Juni 2026 (2026). Method: own measurement. Stadtwerke Düren – Wasserhärte nach §9 WRMG, Analysezeitraum Juli 2025 bis Juni 2026 · Outdated figure? Tell us