Often it's not until some drastic event like a ceiling falling in that people need to start finding a leak. In any aspect of the plumbing within a house, the pipework under the floorboards can suddenly spring a leak. Pipes and fittings which are inlaid into a wall or boxed in can also deteriorate resulting in either a substantial, rapid leak or a more subtle drip. Of the two, the slower leak is the one likely to cause more damage in the long term as the water is absorbed into joists and plaster. Slower leaks and drips are inconspicuous, sometimes continuing for many years.
Here are some common indications that you have an internal leak;
damp spots on carpet
a drip from a ceiling
damp patch appearing on a ceiling
small pool of water
These are the most obvious signs of a subtle leak. However, as with the job I have been called out to today, there were no warnings...until part of the ceiling came crashing down. Unfortunately, this occurred within a block of flats. The tenant who occupies the ground floor flat has not noticed any drips or damp patches - he was most surprised when the ceiling in his kitchen suddenly dropped to the floor followed by a substantial amount of water. Unfortunately, the tenant in the flat directly above was away on holiday, meaning that immediate access was not possible. Once the letting agent arrived to let me in, it was obvious that the leak originated from the bath - one of the pipes which drain the water had corroded, quite a while ago by the looks of it and although the leak was still a drip, it had turned into quite a fast drip. Water had been accumulating for some time - floorboards were soaking wet and mould had started to spread. It is very possible that the ceiling below had begun to show a slight damp patch which had gone unnoticed by the occupant, as it would have been in the corner of the kitchen.
Finding a leak is not always as simple as the above...sometimes the leak is quite simply not where you expect it to be. This is because water will trickle from where it is dripping from, then land and run down the first slanted surface it reaches. Therefore when you discover a pool of water with no obvious water source above, it is because a pipe has leaked and the residual water has travelled. Recently, a letting agent contacted me because a bedroom ceiling was showing signs of a small damp patch. A quick investigation led to a leak on the water tank in the loft but the tank was not above the room with the damp ceiling. The water had dripped onto a framework support under the floor which was angled downwards. Then it followed this course until it reached a groove in the wood which took it in a different direction. From there, it dripped onto the boards above the bedroom - nowhere near the water tank.
