Water hardness in Frankfurt am Main
12.2 °dH very hard
Tap water in Frankfurt am Main is very hard: 12.2 °dH (218 mg/L · 12.7 gpg · 21.8 °fH).
Source: Hessenwasser Wassergüte - Technisch relevante Analysenwerte, Versorgungsgebiet Innenstadt (INN) (2025) · data checked 2026-10-19
Range across supply zones: 71–364 mg/L.
5 supply zones — hardness varies by neighbourhood; the figure above is the median.
Hardness by district / supply zone
| °dH | mg/L | ||
|---|---|---|---|
| Frankfurt Nord (OV) | 11 | 196 | very hard |
| Innenstadt (INN) | 12.2 | 218 | very hard |
| Pendelzone (OVF) | 10.9 | 194 | very hard |
| Pendelzone (PRI) | 15.7 | 279 | very hard |
| Sachsenhausen, Berg- und Talzone, Oberrad (SR) | 13.9 | 248 | very hard |
Hessenwasser blends two supplies, Spessart/Vogelsberg water and harder water from the Hessisches Ried, and the mix changes by district and over time. The five zones give a median of 217.8 mg/L CaCO₃ but a range of 71.4 to 364.1 mg/L, one of the widest in Germany. Check the zone sheet for your area on the Mainova site before relying on the city figure.
German law (WRMG) uses 3 bands: soft < 8.4 °dH, medium 8.4–14 °dH, hard > 14 °dH.
Water data
| Total hardness | 12.2 °dH |
|---|---|
| Utility | Hessenwasser / Mainova |
How Frankfurt am Main compares
- Tap water in Frankfurt am Main is 6 % harder than the median of the 809 cities we track in Germany (11.5 °dH).
- By hardness it ranks 376 of 809 in Germany (1 = hardest); 53 % of these cities have softer water.
- In Hessen it is number 30 of 73 cities; the regional median is 10.7 °dH.
- Nearest city with clearly softer water: Oberursel (Taunus), 13 km away (5.2 °dH).
- Nearest city with clearly harder water: Eschborn, 9 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 Frankfurt am Main
| Brand | Setting for this water |
|---|---|
| Bosch | H04 |
| 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 Frankfurt am Main water hard or soft?
It is very hard: 218 mg/L as CaCO₃ (12.7 gpg, 12.2 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Frankfurt am Main 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 Frankfurt am Main water?
12.7 gpg, equal to 12.2 °dH, 21.8 °fH or 218 mg/L calcium carbonate.
What dishwasher salt setting should I use in Frankfurt am Main?
For 218 mg/L (12.2 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Frankfurt am Main?
Yes, unless you are only passing through: scale damages appliances within a few years.
Source
Source: Hessenwasser Wassergüte - Technisch relevante Analysenwerte, Versorgungsgebiet Innenstadt (INN) (2025). Method: computed from supplier's calcium and magnesium. Hessenwasser Wassergüte - Technisch relevante Analysenwerte, Versorgungsgebiet Innenstadt (INN) · Outdated figure? Tell us