Thank you very much. The detection was very efficient, and much quicker than I expected ! You may like to know that the leak was exactly where your engineer said it was, right next to the soil pipe in the corner. It turned out to be a small hole worn in the underside of the rising cold water main, the copper of which was bright and shiny. It seems that this must have been worn away by a rubbing action against the underlying concrete, as the overlying central heating pipes expanded and contracted, thus pushing the cold main downwards. The lack of visible water from the leak may be due to the water running down the outside of the soil pipe, and along the trench under the floor in which it lies.The leak is now completely fixed.
Graham Travers
