Leaks may occur in a pipe line within the walls, or in the ground, or elsewhere, in such a manner that water escapes into the ground or into the sewer without detection, or the water may escape into the building with resultant damage. In either case the financial loss may be large. The cost of the loss of water through leaky pipes has been variously estimated. The principal factors controlling this are the size of the hole through which the leak is occurring and the pressure of the water.
The location of a leak within the walls or floor of a building requires experience and ingenuity, on the part of the plumber, which should be supplemented by a thorough acquaintance with the piping installation within the building. Usually it is easy to locate a leak in a building but sometimes it is very difficult because, unfortunately, water does not always appear near the point from which it is escaping from the pipe. The tearing out of walls and floors is expensive and can sometimes be avoided by the use of instruments, which depend on the principle of the electric coil and magnetic field for the location of the pipe. In costly buildings X-ray pictures have been used to locate pipes and leaks.
The location of leaks in underground pipes is made possible by various methods.
After a leak has been discovered and it is so located that the water cannot be shut off, if it is possible to stop the leak temporarily, the water in the pipe on the pressure side of the leak can be frozen by the use of a freezing mixture and the repairs made while the pressure is cut off by the plug of ice.
Sometimes a valve can be inserted on the-threaded end of a pipe while water is flowing from the pipe by screwing the valve on the end of a piece of pipe about 6 to 8 ft. long, opening the valve wide, and then screwing it into position handling it with the long piece of pipe. When the valve is in position it can be closed, the piece of pipe removed, and further repairs made with the pressure shut off.