During the following pause Hermione could hear the faucet in the kitchen dripping, and the sound of someone in the stairwell calling up to his wife that he’d forgotten the remembrall and would she grab it for him.  She shut the door behind Harry, then pushed down on the faucet until with a grumble from the pipes the water stopped.  No one spoke until Harry said, "We could keep him in a room at Grimmauld.  There’s a room that locks from the outside.  I’ve never tried to find out why."