The western German city of Koblenz prepared for flooding on Sunday, as meltwater swelled rivers across the country, dpa reported.
Emergency services bolstered flood protection in Koblenz but water began flowing into some cellars, while the Mosel and Rhine rivers were expected to overflow at the point in the city where they meet.
Towns in the wine-growing area along the Mosel river, including Cochem and Zell, had already been inundated with several metres of water earlier in the day.
Across the border, in southern Belgium, emergency services issued the highest level of alert, the Belga news agency reported. Some local authorities distributed bottled water as the flooding contaminated drinking water.
In some parts of Germany, water levels receded slightly, yet in the state of Thuringia, road bridges had to be closed as they were being engulfed by high waters.
A woman and her teenage daughter were dragged 150 metres in their car by rapids in Bavaria, after slipping on an icy road and landing in the river Steinach, north of Bayreuth.
Rail travel had to be diverted away from flooded tracks in the city of Wuppertal, in North-Rhine Westphalia, according to a spokesman for rail operator Deutsche Bahn.
The eastern German state of Saxony-Anhalt also issued top alert levels and experienced initial flooding along secondary rivers.