Prime Minister David Cameron has sent hundreds more troops into northern England to help exhausted residents and emergency workers fight back rising waters.
Cameron said on Sunday the flooding was "unprecedented" and vowed to do all possible to protect people and property as the damage spread to major cities York, Leeds and Manchester.
He said protective systems and contingency plans will be reviewed because the frequency of such extreme weather events seems on the rise.
Weeks of persistent rainfall has saturated the ground and swollen the rivers to record levels, leaving entire swathes of northern England and smaller parts of Wales and Scotland vulnerable. Several hundred flood warnings remain in effect.
There have been no fatalities or serious injuries reported but hundreds of people have been evacuated from houses and apartments in York, 320 kilometres north of London, where 3500 properties are judged to be at risk.
Emergency crews worked extra shifts to try to restore power to roughly 7500 blacked out homes in the greater Manchester and Lancashire areas on Sunday.
Environment Secretary Liz Truss said flood protection systems put in place in recent years were unable to cope.
"In Lancashire every single river was at a record-high," she said.
"In Yorkshire we have seen some rivers a metre higher than they have ever been before. Clearly, in the light of that, we will be reviewing our flood defences."
Several hundred people had been evacuated the day before in the West Yorkshire and Lancashire and officials said thousands had lost power.
The number of people affected continues to grow as flooding spreads and impacts cities as well as villages and towns.
A picturesque 200-year-old pub, The Waterside, in the greater Manchester area, collapsed and part of the structure was swept away by the River Irwell.
