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Repairing a Compression Joint

When you find a leaking compression joint the first thing you should try is tightening the cap-nut on the end of the fitting using two wrenches (one to hold the body of the fitting and the other to turn the cap-nut clockwise to tighten it).

Disassembling the joint

If the joint still leaks after tightening the cap-nut you will have to disassemble the fitting to look inside it to see what the problem is (remember to turn of the water supply and drain the pipe first). Use two wrenches (one to hold the body of the fitting and the other to turn the cap-nut anti-clockwise to loosen it. If you are unable to loosen the cap-nut, you'll have to cut it out with a hacksaw and replace the fitting.

Once you have unscrewed one of the cap-nuts there will be enough movement in the pipe run to allow you to pull the pipe from the casing of the fitting. Usually you will find that the olive has been compressed against the pipe. You need to check the olive - some have symmetrical sloping sides, but some have long and short sloping sides. With an olive that has long and short sloping sides, the long side must face the body of the fitting.

If the olive is too tight to remove from the pipe, you will need to cut it off with a hacksaw. It is easiest to cut it diagonally (be careful not to damage the pipe).

Reassembling the joint

Check that the end of the pipes are square - if not you will not get a good connection. Remove any burrs on the end of the pipes. Clean the end of the pipes and the olive with with steel wool or emery paper until they are shiny. Always use a new olive - you can buy them in DIY stores (but be careful to get the right one). Slip on the olive (make sure it is facing the correct way) and finger tighten the cap-nut. Rotate the cap-nut 1 1/2 turns using the wrenches.

Finally, turn on the water supply to check that the joint is now is no longer leaking.