Düsseldorf obtains its water almost entirely as bank filtrate of the Rhine in the Flehe, Holthausen and Am Staad waterworks. It is treated with ozone and activated carbon, and is hard but very clean.
Water hardness
15.5 °dHhardA lot of calcium and magnesium: good for the body, a nuisance for appliances. Descale regularly and use more detergent. Descale: every 4 weeks.
Aquaviana’s advice
- Hardness is 14 to 17 °dH, so descale regularly.
- The activated carbon process is regarded as a model; the water is free of taste-affecting substances.
- Düsseldorf has many drinking fountains, including on the banks of the Rhine and in parks.
Where the water comes from
Wells near the Rhine draw water that has seeped for 40 to 60 days through the gravel and sand layers of the bank. On this journey, suspended particles and most germs are removed. Then comes the “Düsseldorf process”: ozone oxidises organic substances, and activated carbon binds them. This process was developed here in the 1960s and is now the worldwide standard for river water.
Hardness and taste
The water is hard, 14 to 17 °dH (about 250 to 300 mg/l CaCO3), with calcium around 90 mg/l and magnesium around 12. It tastes full and clean, with no taste of chlorine or earth, because the activated carbon removes taste-affecting substances. Nitrate is under 15 mg/l.
What that means day to day
Limescale as in Cologne: descale every four to six weeks, and use a jug filter for tea and coffee. Otherwise it is a water you can drink from the tap without hesitation, and you would never notice its closeness to the Rhine. The municipal utility (Stadtwerke) publishes the analysis by waterworks.
Try it out
Hardness converterConvert °dH, °fH, °e, mmol/l and ppm into one another and read off the hardness range and descaling interval.Tap water checkEight questions about your home, pipes and region, an assessment with a traffic light and next steps.Share
