Some residents in a flood-stricken village could be out of their homes for up to three weeks as efforts continue to make the area safe.
Fishlake near Doncaster has been one of the worst hit with hundreds of people being forced to leave their properties.
About 100 Army personnel are in South Yorkshire supporting the flood effort.
The prime minister is visiting a flood-hit area to see the emergency response. But some onlookers shouted at him to say "you took your time Boris".
Doncaster Council said every effort was being made to increase pumping so people could return home sooner.
More widespread rain is forecast, with warnings in place for large parts of the country on Wednesday and Thursday.