Water hardness in Olfen
11.3 °dH very hard
Tap water in Olfen is very hard: 11.3 °dH (202 mg/L · 11.8 gpg · 20.2 °fH).
Source: Gelsenwasser AG, Wasserhärte nach Ort (2026) · data checked 2026-10-20
Gelsenwasser reports 201.7 mg/L CaCO₃ for Olfen in its 2026 locality table, in the very hard category. We hold no range for the town. Limescale forms quickly on heating elements and taps.
German law (WRMG) uses 3 bands: soft < 8.4 °dH, medium 8.4–14 °dH, hard > 14 °dH.
Water data
| Total hardness | 11.3 °dH |
|---|
How Olfen compares
- Tap water in Olfen is close to the median of the 809 cities we track in Germany (11.5 °dH).
- By hardness it ranks 413 of 809 in Germany (1 = hardest); 48 % of these cities have softer water.
- In Nordrhein-Westfalen it is number 70 of 153 cities; the regional median is 11.3 °dH.
- Nearest city with clearly softer water: Lünen, 14 km away (7.8 °dH).
- Nearest city with clearly harder water: Raesfeld, 31 km away (14.3 °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 Olfen
| Brand | Setting for this water |
|---|---|
| Bosch | H03 |
| Miele | 11 °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 Olfen water hard or soft?
It is very hard: 202 mg/L as CaCO₃ (11.8 gpg, 11.3 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Olfen 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 Olfen water?
11.8 gpg, equal to 11.3 °dH, 20.2 °fH or 202 mg/L calcium carbonate.
What dishwasher salt setting should I use in Olfen?
For 202 mg/L (11.3 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Olfen?
Yes, unless you are only passing through: scale damages appliances within a few years.
Source
Source: Gelsenwasser AG, Wasserhärte nach Ort (2026). Method: figure published by the water supplier. Gelsenwasser AG, Wasserhärte nach Ort · Outdated figure? Tell us