Test installation for drinking water softening

Many Danish water utilities and consumers are interested in softening hard Danish drinking water by removing calcium carbonate. Potential benefits are reduced soap and energy consumption as well as increased life expectancy for pipe installations and domestic appliances.

Using a small-scale demonstration “pilot plant”, we offer insights and thorough testing of drinking water softening using the pellet fluid bed method. The test installation is also available for hire to other utilities interested in testing the potential for softening by pellet reactor.

How it works

The test installation consists of a pellet reactor and a sand filter. Inlet water is mixed with fine sand and a strong base, which causes calcium carbonate to precipitate on the sand grains. The limestone pellets formed are removed and replaced with new sand. The water’s pH value is then adjusted by adding carbon dioxide, and eventually the softened water is pumped through the sand filter column.

The pilot plant is equipped with online meters to monitor continuously: pH, conductivity, turbidity and oxygen content. There is also a simple mini-lab for supplementary field tests.

Areas of use

The installation is built into three containers, so that it can be easily moved and utilized in both medium-sized and large water utilities.

This solution enables water utilities to investigate how the softening process will affect their water quality. At the same time, the pilot plant provides important design information for dimensioning full scale plants.

Solution partners

This solution is part of the Future Water R&D initiative. The solution is developed by HOFOR in cooperation with Technical University of Denmark and VCS Denmark.

For more information, visit the website or contact project director Henrik Juul (, +45 40 82 36 10)

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VCS Denmark
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Primary contact
Henrik Juul
+45 40 82 36 10