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Raising the Bar for Danish Tap Water

Raising the Bar for Danish Tap Water

In order to remove tap water's content of calcium, the Danish utility company HOFOR is establishing a new plant for softening water. By using descaled water, the capital region of Denmark could save DKK 228 million annually and the average consumer will no longer have to endure as many problems associated with limescale.

By State of Green, 2017.02.16

Denmark is characterised by a stable and sustainable source of high-quality water from groundwater abstraction. Without any chemicals added, it is superior to most bottled water. In 2013, the World Economic Forum even ranked Denmark number one in the world on access to water, sanitation, and hygiene.

Yet despite of these achievements, water utilises in Denmark also face challenges. One of which has been the high content of calcium in tap water – a problem for many as limescale causes problems for machines, installations, taps, toilets, and surfaces in damp areas. The Danish utility company HOFOR has now dealt with this problem head-on as they are adding a new plant for descaling water at one of their utilities.

- Download State of Green's white paper on water supply


White paper: Ensuring great-tasting and save tap water 24 hours a day

Since the groundwater in Copenhagen and the rest of Eastern Denmark contains a high level of calcium – as oppose to the Western part of Jutland where the water is softer due to differences in the soil layers that the groundwater passes through, the new plant will be located in Brøndby near Copenhagen.

By softening the water, HOFOR plans to reduce the troubles that many of their consumers face. Less calcium in the water would also mean a significant reduction of energy consumption for appliances and heating plants. Per Sand Rosshaug, the strategic planner at HOFOR, explains:

There are many socioeconomic and environmental benefits from softening the water. Consumers will not have to spend as much time on decalcification and maintenance of bathrooms and coffee machines. Washing machines and kettles will have a longer life span as limescale will not appear as quickly. Appliances will use less energy as there will not be need for heating of limescale on the heating units. Consumers will also have to use less washing powder when applying softened water.

- Related news: New Method for Predicting Movement in Groundwater

Towards 2024, Hofor will readjust more of their utilities to ensure that all their consumers get access to descaled water. They hope that by 2024, all of the municipalties within their supply area will be receiving the softened water.

HOFOR’s calculations convey that the average family of four in Copenhagen can save about DKK 500 a year due to descaledwater. And the consultancy group Cowi estimated that the capital region could save DKK 228 million on an annual basis.

The technology for softening the water is entitled “the pellet method”.  It was originally developed in the Netherlands where it gained currency during the 1970s. 

According to ph.d.-student Camilla Tang, the process of softening the water is the opposite of descaling kettles:

- In a kettle, the limscale is deposited when you add an acid to dissolve it. At water utilities, the limscale is still  dissolved in the water which is why you add a base to make the limscale deposit like small pills that you can remove. Afterwards, you neutralise the water again before directing it to the consumers. The point is to get the limescale to deposit at the water utility instead of at the home of the consumers.

Related news: New system to Control Water Pressure and Leakages

In practical terms, they send small grains of sand through the water which connect to the limescale. The water will not taste any differently in the process and the water quality will stay intact, explains Camilla Tang.

As a part of her PhD thesis, she is collaborating with DTU Environment, HOFOR, and the consultancy company Niras in order to examine how to achieve the most sustainable softening process possible. They are currently examining different ways of reusing the water’s calcium in agriculture.

The new water treatment plant will be ready later this year.

- Download State of Green's white paper on groundwater security


White paper: Greater water security with groundwater

- Sources: Politiken & HOFOR

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