Into rivers that take it to the sea. There are only a limited number of places where this is effective. If the river has burst its banks, there's no point pumping water round in circles.
Apparently there is the same amount of water on earth and earths atmosphere as there was when it was first formed - it's just all in a different place. I'm a mine of totally useless information, me.
Back in the 60's we lived in a house where the back garden flooded (nowhere near a river) so my dad just dug a ditch at the end of the garden. Result; next year the neighbors where out digging theirs.
So perhaps this is what people should do. Take their destiny into their own hands and stop waiting for others to do something for them and for nothing.
Its often said that Londoners drink water that has already passed through 4 sets of kidneys, although I have never been terribly sure how they can be that exact. In Wales, we drink very, very, very, very weak sheeps pee.