Water hardness in Bornheim (Rhein-Sieg)
12 °dH very hard
Tap water in Bornheim (Rhein-Sieg) is very hard: 12 °dH (214 mg/L · 12.5 gpg · 21.4 °fH).
Source: Stadt Bornheim Netzproben Prüfbericht PB2607088 (2026-06) · data checked 2026-10-22
Range across supply zones: 179–214 mg/L.
7 supply zones — hardness varies by neighbourhood; the figure above is the median.
Hardness by district / supply zone
| °dH | mg/L | ||
|---|---|---|---|
| Hersel (Schule, Rheinstr. 182) | 12 | 214 | very hard |
| Merten (Schule, Beethovenstr. 57) | 12 | 214 | very hard |
| Rathaus (Rathausstr.) | 11 | 196 | very hard |
| Roisdorf (Schule, Friedrichstr. 3) | 12 | 214 | very hard |
| Sechtem (Schule, Brackstr.) | 10 | 179 | hard |
| Walberberg (Schule, Walburgisstr.) | 10 | 179 | hard |
| Wasserwerk Eichenkamp, Ausgang (Uedorfer Weg) | 12 | 214 | very hard |
A network sample report from June 2026 for the Bornheim municipal waterworks gives 214.2 mg/L CaCO₃. The town has seven zones, with values from 178.5 to 214.2 mg/L, so the figure shown is the upper end. Bonn (99.1 mg/L) and Troisdorf (96.4 mg/L) are only 4 to 6 km away and much softer. Do not assume your neighbours across the town line have the same water.
German law (WRMG) uses 3 bands: soft < 8.4 °dH, medium 8.4–14 °dH, hard > 14 °dH.
Water data
| Total hardness | 12 °dH |
|---|---|
| Utility | Wasserwerk der Stadt Bornheim (StadtBetrieb Bornheim AöR) |
How Bornheim (Rhein-Sieg) compares
- Tap water in Bornheim (Rhein-Sieg) is close to the median of the 809 cities we track in Germany (11.5 °dH).
- By hardness it ranks 381 of 809 in Germany (1 = hardest); 52 % of these cities have softer water.
- In Nordrhein-Westfalen it is number 64 of 153 cities; the regional median is 11.3 °dH.
- Nearest city with clearly softer water: Bonn, 4 km away (5.6 °dH).
- Nearest city with clearly harder water: Cologne, 20 km away (16.9 °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 Bornheim (Rhein-Sieg)
| Brand | Setting for this water |
|---|---|
| Bosch | H03 |
| Miele | 12 °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 Bornheim (Rhein-Sieg) water hard or soft?
It is very hard: 214 mg/L as CaCO₃ (12.5 gpg, 12 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Bornheim (Rhein-Sieg) 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 Bornheim (Rhein-Sieg) water?
12.5 gpg, equal to 12 °dH, 21.4 °fH or 214 mg/L calcium carbonate.
What dishwasher salt setting should I use in Bornheim (Rhein-Sieg)?
For 214 mg/L (12 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Bornheim (Rhein-Sieg)?
Yes, unless you are only passing through: scale damages appliances within a few years.
Source
Source: Stadt Bornheim Netzproben Prüfbericht PB2607088 (2026-06). Method: own measurement. Stadt Bornheim Netzproben Prüfbericht PB2607088 · Outdated figure? Tell us