Water hardness in Hamm
7.8 °dH hard
Tap water in Hamm is hard: 7.8 °dH (139 mg/L · 8.1 gpg · 13.9 °fH).
Source: EWV Hamm - Jahrestrinkwasseranalyse 2025 (Jahresmittelwerte) (2025) · data checked 2026-10-19
Range across supply zones: 129–148 mg/L.
3 supply zones — hardness varies by neighbourhood; the figure above is the median.
Hardness by district / supply zone
| °dH | mg/L | ||
|---|---|---|---|
| Wasserwerk Echthausen (Wasserwerke Westfalen) | 7.2 | 129 | hard |
| Wasserwerk Halingen (Wasserwerke Westfalen) | 7.8 | 139 | hard |
| Wasserwerk Warmen (EWV Hamm) | 8.3 | 148 | hard |
Hamm's 2025 annual analysis lists three supplies: the EWV Warmen works and the Echthausen and Halingen works of Wasserwerke Westfalen. The median is 139.2 mg/L CaCO₃ and the range is 128.5 to 148.2 mg/L. The printed column headers do not map cleanly to the three values, so the assignment of values to works is uncertain. The spread is small, so the choice of works changes little.
German law (WRMG) uses 3 bands: soft < 8.4 °dH, medium 8.4–14 °dH, hard > 14 °dH.
Water data
| Total hardness | 7.8 °dH |
|---|
How Hamm compares
- Tap water in Hamm is 32 % softer than the median of the 809 cities we track in Germany (11.5 °dH).
- By hardness it ranks 579 of 809 in Germany (1 = hardest); 28 % of these cities have softer water.
- In Nordrhein-Westfalen it is number 112 of 153 cities; the regional median is 11.3 °dH.
- Nearest city with clearly softer water: Werdohl, 46 km away (2.3 °dH).
- Nearest city with clearly harder water: Nordkirchen, 21 km away (10.8 °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 Hamm
| Brand | Setting for this water |
|---|---|
| Bosch | H01 |
| Miele | 8 °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 Hamm water hard or soft?
It is hard: 139 mg/L as CaCO₃ (8.1 gpg, 7.8 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Hamm 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 Hamm water?
8.1 gpg, equal to 7.8 °dH, 13.9 °fH or 139 mg/L calcium carbonate.
What dishwasher salt setting should I use in Hamm?
For 139 mg/L (7.8 °dH) check your manufacturer's table: level 4–5.
Do I need a water softener in Hamm?
Recommended if you have a water heater, boiler or tankless unit: it saves repairs and detergent.
Source
Source: EWV Hamm - Jahrestrinkwasseranalyse 2025 (Jahresmittelwerte) (2025). Method: figure published by the water supplier. EWV Hamm - Jahrestrinkwasseranalyse 2025 (Jahresmittelwerte) · Outdated figure? Tell us