From water bubbles in older coating to safe drinking water solution

Undløse Vandværk
Task types
Water bubbles in your coated clean water tanks? This was the challenge which Undløse Vandværk, a private waterworks in the Municipality of Holbæk on Zealand, faced in November 2021.

Lennart Nilsson, treasurer at Undløse Vandværk, therefore contacted Dansk Plast after coming across our drinking water solutions on our website.

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Water bubbles in the coating

In 2011, Undløse Vandværk decided to renovate their concrete clean water tanks by coating them. When, in 2016, they inspected the tanks, they could already observe signs of water bubbles/clustering in the coating. It was deemed that the tanks only had five more years of service life in them.
In November 2021, it was again time for an inspection. By this stage, the condition of the tanks was so poor that Undløse Vandværk decided to consider a different renovation solution, as they were worried about the potential consequences.

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Inspection and measurement

Lennart, the treasurer at Undløse Vandværk, came across Dansk Plast via our website. On the website, he read about a case study from the waterworks Snolderlev Vandværk, where we had previously renovated their reaction tank. Lennart contacted Snolderlev Vandværk, which warmly recommended Dansk Plast.

In March 2022, Dansk Plast visited Undløse Vandværk, where we inspected and measured up the tanks.

After our quotation was considered and approved by the waterworks board, we started the actual renovation work in mid-April.

Renovering Undløse Vandværk 11

Effective installation

Dansk Plast sent three experienced fitters for the task, and we could thereby ensure that the work was carried out efficiently and professionally, as we knew that it was important for the waterworks to keep downtime to an absolute minimum.

It took our fitters two weeks to fit the 4 mm PEHD sheets with backing spacers. Once work on the tank was finished, this would ensure that the clean water is only ever in contact with materials approved for use with drinking water.

When, at the beginning of May 2022, we paid a final visit, both clean water tanks were in full operation. In other words, only three months had elapsed from when Undløse Vandværk first contacted us and until the task was finished, of which two weeks were spent conducting the actual renovation work.


Lennart Nilsson, treasurer, Undløse Vandværk

"The board is very satisfied with everything relating to the work which has been carried out for us by Dansk Plast. We can only recommend other waterworks to get in touch with them. All the contact we have had with the employees – from the management to the fitters – has been extremely satisfactory. And the result is that we hopefully won’t have to think about these tanks for many years, apart from cleaning the bottoms perhaps. Other waterworks have seen the result, and are very impressed. We envisage there are numerous water tanks in Denmark that ought to be treated in this way. Thank you for the excellent collaboration."
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Operations during renovation work

How can one maintain supplies during renovation work?

If, like Undløse Vandværk, you have two or more tanks, it’s possible to keep running using one tank while performing the renovation work on the other.

On the other hand, if you only have one tank, and no possibility for providing emergency supplies, it is possible to hire a mobile clean water tank from Dansk Plast, so that the waterworks can continue to supply water during the renovation.

However, Undløse Vandværk decided to obtain supplies from a nearby waterworks while the work took place.