Daughter's house: source of leak not found

A couple of weeks ago I was on the phone to our daughter. She was in the middle of telling me how the chocolate drink she'd been heating in the microwave had just exploded out of the mug, when she noticed that water was running down the kitchen wall. There was a growing damp patch on the ceiling in the corner below the bathroom. The story of the microwave mishap was put on hold while Ally and Ben investigated the worrying wetness. There was water also running down the wall in the bathroom. (Now, why is everywhere so far from Norwich?)

Right, do the obvious, turn off the water. Then check in the loft for a leak. Well, they couldn't find anything. There weren't even any pipes in the loft as there's no cold water cistern.

In the days since then they've been turning the water on and off at the stopcock as required, and the damp retreated.


To cut to today: a plumber came, attacked tiles with a hammer and opened up a hole by the bath. Peering in with a torch and mirror revealed no damp whatsoever. This completely foxed the plumber. There seemed to be absolutely nowhere for the water to have come from.




So the water has been left on with Ally and Ben monitoring the situation. Hardly satisfactory, but at least I can say that if a professional plumber couldn't find a leak then I wouldn't have been able to either.

One thing: when Ally and Ben moved in there was an occasional water drip from the boiler, which stopped after a few weeks. I mentioned this on the phone to the plumber, and he looked and saw that the pressure was reading zero. He repressurised it, and he went. Now I'm wondering whether this could be significant. Could it be that there was a leak from the radiator system which took the pressure down to nothing? And now that it's been repressurised will it all start again? I have to admit not knowing much about central heating systems and modern - any - boilers. I don't know what is under pressure and why.


I think the most likely explanation is that snow blew in under the eaves, sat in a pile in the loft, and melted. Some water could also have got in when snow melted on the roof of the lean-to utility room.


If anyone reading this far has any ideas I'd be glad to hear them!