Water hardness in Rendsburg
10.6 °dH very hard
Tap water in Rendsburg is very hard: 10.6 °dH (190 mg/L · 11.1 gpg · 19 °fH).
Source: Stadtwerke SH Trinkwassergebiete Rendsburg, Wasseruntersuchung per Wasserwerk (2026-05) · data checked 2026-10-23
Range across supply zones: 152–229 mg/L.
2 supply zones — hardness varies by neighbourhood; the figure above is the median.
Hardness by district / supply zone
| °dH | mg/L | ||
|---|---|---|---|
| Wasserwerk Am Armensee | 12.8 | 229 | very hard |
| Wasserwerk RD-Süd (Schwabe) | 8.5 | 152 | hard |
Stadtwerke SH lists results per waterworks for Rendsburg, last updated in May 2026. Am Armensee is at 228.5 mg/L CaCO₃ and RD-Süd (Schwabe) at 151.7 mg/L. The city figure is 190.1 mg/L. That is harder than Flensburg (140.1 mg/L) and softer than Kiel (300.8 mg/L).
German law (WRMG) uses 3 bands: soft < 8.4 °dH, medium 8.4–14 °dH, hard > 14 °dH.
Water data
| Total hardness | 10.6 °dH |
|---|---|
| Utility | Stadtwerke Rendsburg GmbH (Stadtwerke SH group) |
How Rendsburg compares
- Tap water in Rendsburg is 7 % softer than the median of the 809 cities we track in Germany (11.5 °dH).
- By hardness it ranks 459 of 809 in Germany (1 = hardest); 43 % of these cities have softer water.
- In Schleswig-Holstein it is number 18 of 26 cities; the regional median is 12 °dH.
- Nearest city with clearly softer water: Hohenlockstedt, 38 km away (6.3 °dH).
- Nearest city with clearly harder water: Eckernförde, 21 km away (15.6 °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 Rendsburg
| Brand | Setting for this water |
|---|---|
| Bosch | H03 |
| Miele | 11 °dH |
| AEG / Electrolux | 2 |
| 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 Rendsburg water hard or soft?
It is very hard: 190 mg/L as CaCO₃ (11.1 gpg, 10.6 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Rendsburg 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 Rendsburg water?
11.1 gpg, equal to 10.6 °dH, 19 °fH or 190 mg/L calcium carbonate.
What dishwasher salt setting should I use in Rendsburg?
For 190 mg/L (10.6 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Rendsburg?
Yes, unless you are only passing through: scale damages appliances within a few years.
Source
Source: Stadtwerke SH Trinkwassergebiete Rendsburg, Wasseruntersuchung per Wasserwerk (2026-05). Method: figure published by the water supplier. Stadtwerke SH Trinkwassergebiete Rendsburg, Wasseruntersuchung per Wasserwerk · Outdated figure? Tell us