With rivers bursting their banks and groundwater brimming at the surface, the additional rainwater will put additional pressure on the underground sewers which are already full.
The firm, which operates more than 67,000 miles of sewers, has been struggling in some areas to cope with the additional water filling up its pipes.
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Friday night's forecast for the west of the region
It's a Bank Holiday weekend, with half term for many. Here's how it's looking on the roads, in the skies, and at getaway hotspots