How to Mend Leaking or Broken Water Pipes
MENDING LEAKS IN PIPEWORK
Where a pipe or joint has already burst, calling for emergency repairs, there remains the problem of how to repair the damage permanently. Fortunately, modern plumbing fittings have put the job firmly within the scope of the do-it-yourselfer — even when the damage is on an old iron or lead pipe.
All of the repairs shown here use basic plumbing tools — wrenches for undoing pipes, hacksaws for cutting them, and PTFE tape for remaking the joints. In the case of soldered joints, you’ll also need a blowtorch and heat-proof mat, plus supplies of self-cleaning flux and solder. When it comes to buying new pipe and fittings, the important thing is to know what pipe size you’re dealing with. If necessary, check the external diameter and quote this to your supplier.
Check the size
"Check the external diameter of a leaking pipe with a pair of school compasses. Metric copper pipe and most plastic pipe is actually measured on the external diameter. On iron, lead, and old Imperial copper, the internal diameter is the one quoted by stockists, but you’ll get a close enough idea."
LEAKING COMPRESSION JOINTS
Most leaks on compression joints are caused by over or under-tightening; the difficulty is knowing which.
If there is some thread left showing, try tightening the nut (clockwise) a half-turn. If this doesn’t work — or there is no visible thread to start with — turn off the water; drain down the pipe, and dismantle the leaking side of the fitting.
Check that the pipe end reaches as far as the internal stop, with the sealing ring (olive) hard against the fitting. If the pipe is too short, you’ll
have to patch in a new section. If the olive is wrongly positioned, you may be able to tap it further along the pipe. However, it’s safer to saw through the old olive with a— taking care not to damage the pipe end — then fit a new one.
If everything looks as it should do, wrap a couple of turns of PTFE tape around the fitting side of the olive, keeping it clear of the cut pipe end, or lightly smear it with jointing compound (eg Boss Blue, Fernox XLS). Then remake the joint.
LEAKING THREADED JOINTS
Old-fashioned threaded joints in iron pipe were sealed with hemp and linseed oil compound. After years in service, the hemp can rot and allow water to seep through —although this usually results in an annoying drip rather than a jet of water.
1. Undo the necessary joints, using a Stillson-type wrench to grip the threaded pipe. If any are stiff, apply a little heat to soften the old jointing compound.
2. Scrape off all traces of old compound from the thread, and wrap it with at least five clockwise turns of PTFE tape before remaking each joint
LEAKING SOLDERED JOINTS
Leaks in soldered joints are usually caused by dirt stopping the solder running freely in the first place. So long as the pipe can be drained completely it’s usually possible to solve the problem by heating the joint with a blowtorch, and then feeding in a generous amount of self-cleaning flux followed immediately by a short length of solder. This works on pre-soldered joints as well as the end feed type.
Otherwise, it’s best to fit a new joint. Sever the old one in the middle, then heat up both sides and remove them. Clean and re-solder.
Patch an existing joint by heating until the solder bubbles, then feeding in fresh flux and solder. If the solder is drawn in, you know it has worked
To dismantle a leaking joint, saw through the middle, then heat both sides to remove the cut fitting. Clean off all traces of old solder with steel wool.