No, not a medical problem - I mean there's a constant slow dribble of water from the cistern into the toilet bowl. There's a slight giveaway ripple, plus I tested it with one of those dye tablets from the water board and the colour came through quite quickly. The toilet is a close-coupled Armitage Shanks (something like this) with one of those weird compact push-button dual-flush valves that have a flimsy plastic cup as a float valve instead of a ballcock (see here for example). I'm told it could be as simple as replacing the seal beneath the valve, but that it could also be a false economy as the valve itself might be on the way out. Not sure how old it is - at least 6 years but maybe more (was here when we moved in). Can anyone advise on how easy (or not) it would be for an untrained DIY-er to replace the valve, and alternatively a ballpark cost for a professional to do it (parts cost looks to be about £30 but no idea about labour)?