An experimental outdoor swimming pool in Brussels is to remain shut as its eco-friendly filtration system is unable to keep the water clean.
Situated by a scenic concrete canal in Anderlecht, it seems Brussels citizens keen for a cooling dip will have to suffer a while longer in the humid summer heat.
Flow is an annual project set up in 2021 that aims to bring back outdoor swimming to the Brussels region. It is organised by a local advocacy group called “Pool is Cool.” The Flow pool itself is a large temporary construction intended to operate over the hottest months.
In the first two years, it used a standard filtration system to keep the pool clean that involves putting small doses of highly-toxic chlorine into the water to kill all bacteria. Other chemicals such as sulphuric acid are also usually added to maintain the water’s chemical balance.
However, this year the project leaders decided to try the more environmentally friendly and sustainable method of biological water filtration. This sends the pool’s dirty water through a series of tanks containing different combinations of gravel, microscopic organisms and even small water plants.
A number of Belgian outdoor pools in Wallonia and Flanders already use this method.
However, it appears that, for now, Brussels’ own experimentation with the so-called “piscine plein air” system has had its ‘Flow’ interrupted. Still, management seems hopeful about the pool’s prospects.
The latest update on the group’s website says that contamination levels have fallen by half since the last test on July 7. While they are still too high to allow public use, management wrote that they “are optimistic that we can reopen this week”.
Pool is Cool maintains that the biological treatment system takes a while to become effective. With a number of other pools across Belgium and the world, and the method having been around for some years, they may yet be right.
Brussels’ swimmers hoping to avoid heatstroke will certainly hope they are.