A third of Brussels cellars at risk of flooding during heavy rain

One in three cellars in Brussels are likely to flood during heavy rains, according to a new, interactive map from Brussels Environment.

The map provides a detailed overview of flood risk throughout the capital and offers tips on how to protect basements. It is an update of the previous map, adapted to the latest European requirements. 

“Following this summer’s heatwaves, we are preparing for an autumn of heavy rain and stormy weather,” said Ans Persoons (Vooruit), Brussels state secretary for the environment, climate and urban renewal.

“We want to equip Brussels and its residents as well as possible to cope with the effects of climate change. The tool offers simple tips that can make a difference quickly and without costly interventions. We must do everything we can to prevent rainwater from entering the sewer system.”

From the new flood map, users will be directed to solutions and tools to tackle issues such as water in the cellar.

These often do not involve major structural work in residential properties, according to Brussels Environment, but rather solutions that can sometimes alleviate major concerns even on a small budget. 

These solutions range from sandbags that can be placed in front of window openings when a warning is issued, to more professional flood barriers, and preventative modifications such as installing a speed bump at the top of a garage ramp.

In the Brussels region, it is primarily the low-lying valley areas that are vulnerable to flooding: the Senne valley, the Molenbeek valley, the Maelbeek valley and the Woluwe valley.

The greatest risk of flooding is linked to sewage backing up into basements, affecting almost one in three Brussels residents during heavy rainfall or storms. 

Preventive action is essential, said Persoons.

“There are many measures we are already taking to make a difference: rainwater must be disconnected from the sewerage network in new-build projects,” she added.