Five people have died in the city of Verviers; two in Chaudfontaine; one in Eupen, Pepinster, Aywaille and Philippeville each, Le Soir news outlet reported on late Thursday.
The list of the missing people includes a 15-year-old girl from the province of Luxembourg.
The floods caused by heavy rainfall have mostly hit the provinces of Liege, Namur and Walloon Brabant while the provinces of Luxembourg, Antwerp and Flemish Brabant also faced significant damage.
The floods in neighboring Germany have already claimed at least 58 lives. In Netherlands, at least 15,000 people are being evacuated as floodwater levels continue to rise in the southeast of the country.