Water hardness in Castrop-Rauxel
9.3 °dH hard
Tap water in Castrop-Rauxel is hard: 9.3 °dH (166 mg/L · 9.7 gpg · 16.6 °fH).
Source: Gelsenwasser AG, Wasserhärte nach Ort (2026) · data checked 2026-10-20
Range across supply zones: 130–202 mg/L.
Gelsenwasser reports 166.0 mg/L CaCO₃ for Castrop-Rauxel, within a band of 130.3 to 201.7 mg/L. The water is hard, and the supply area covers both ends of that band. If you plan to buy a softener, confirm which value applies to your street.
German law (WRMG) uses 3 bands: soft < 8.4 °dH, medium 8.4–14 °dH, hard > 14 °dH.
Water data
| Total hardness | 9.3 °dH |
|---|
How Castrop-Rauxel compares
- Tap water in Castrop-Rauxel is 19 % softer than the median of the 809 cities we track in Germany (11.5 °dH).
- By hardness it ranks 506 of 809 in Germany (1 = hardest); 37 % of these cities have softer water.
- In Nordrhein-Westfalen it is number 99 of 153 cities; the regional median is 11.3 °dH.
- Nearest city with clearly softer water: Essen, 24 km away (6.6 °dH).
- Nearest city with clearly harder water: Gladbeck, 23 km away (13.5 °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 Castrop-Rauxel
| Brand | Setting for this water |
|---|---|
| Bosch | H02 |
| Miele | 9 °dH |
| AEG / Electrolux | 2 |
| Beko | 3rd |
| 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 Castrop-Rauxel water hard or soft?
It is hard: 166 mg/L as CaCO₃ (9.7 gpg, 9.3 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Castrop-Rauxel 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 Castrop-Rauxel water?
9.7 gpg, equal to 9.3 °dH, 16.6 °fH or 166 mg/L calcium carbonate.
What dishwasher salt setting should I use in Castrop-Rauxel?
For 166 mg/L (9.3 °dH) check your manufacturer's table: level 4–5.
Do I need a water softener in Castrop-Rauxel?
Recommended if you have a water heater, boiler or tankless unit: it saves repairs and detergent.
Source
Source: Gelsenwasser AG, Wasserhärte nach Ort (2026). Method: figure published by the water supplier. Gelsenwasser AG, Wasserhärte nach Ort · Outdated figure? Tell us