Hotpoint WD61 Leaking Water Into Drum?? HELP?

Hi

I have a Hotpoint WD61 which has been fine for some time now, however recently it has started leaking water into the drum whilst it is sat idle. If you leave it for a couple of days without using the machine then it fills up the drum enough to come spilling out when you open the door. Not only is this really annoying but I guess its also wasting quite a bit of water. Does anyone know whats at fault here and how Id go about fixing it?

Thanks