There are three main types of joints used in domestic plumbing systems and knowing how to repair a leak or replace a leaking fitting can save you money. The types we are going to look at are soldered joints, compression joints, and push-fit connections.
Soldered joints can be split into two categories – those with an integral solder ring, which are the most popular type used in DIY plumbing, and end feed solder fittings which are more commonly used by professional plumbers.
But, as any plumber will tell you, once the water has got into the joint, it can be very difficult to re-solder it and create a properly sealed joint. In fact, this is one of the reasons that a soldered joint may leak in the first place. Other reasons include incomplete soldering where the solder has not fully sealed between the two surfaces due to uneven heating of solder application. Soldering joints in copper pipe relies on the copper being cleaned properly and the joint being completely dry. Realistically, this is very difficult to achieve with and old joint so, the best answer with a failed soldered joint is to simply replace it. This will usually involve cutting the pipe and replacing a short section with a new integral solder fitting at each end.
Drain down the water pipe and cut out a small section so that you can fit a new short length and two fittings. Use a pipe cutter to do this so that you are left with good clean cuts and deburr the ends. Make sure that the pipe is completely dry before starting work otherwise you will be back to square one. Clean the pipe ends with emery paper or a pipe cleaning tool. Apply a little flux around the pipe ends and assemble the new section using integral solder fittings. Rotate the pipe and fittings to ensure that the flux has properly coated both surfaces. Before heating the joints, make sure that there is no combustible material nearby and use a heatproof mat to guard the area. Apply heat evenly all around each fitting until the solder just begins to show as a ring around both ends of the fitting, then remove the heat. Allow the fitting to cool and clean the outer surface to remove all residue. Finally, open the supply again and check the joints. Allow the water to flush through the pipework thoroughly to remove any contaminants
Leaking compression joints can sometimes be relatively easy to fix. Compression joints rely on the olive being compressed between the fitting and the pipe to form the seal.
Nipping up the Joint
It may be that a seal can be achieved by nipping up the joint, but you need to be aware that over tightening can make the leak a lot worse. Holding the body of the joint with a pipe wrench to prevent it moving or twisting, use a spanner or second wrench to tighten the offending connection a little. If a small amount of tightening doesn’t resolve it, don’t continue – you will need to refit the joint.
To refit the joint or fit a new one, you will need to switch off the water to this pipework and drain down. Carefully undo the fitting on the side that is leaking using a wrench to hold the centre section and prevent it from turning while you undo the end nut. Slide the nut back along the pipework and open up the joint. This may require a bit of force as the pipe end sits inside the joint a little way. If the olive is in good condition, it may be possible to wrap a few turns of PTFE tape around it allowing it to be reassembled and sealed.
Otherwise, the olive will need to be replaced. Grip it gently with a wrench and work it back off the end of the pipe. If it’s stubborn, cut through it carefully at an angle using a junior hack saw. Take care not to damage the pipe at all. Remove the olive and clean the pipe before fitting a new one. Reassemble the joint making sure that the pipe end fits fully up to the internal stop inside the fitting. Slip the nut back down to the threaded part of the fitting and hand tighten. Hold the body of the connection with a wrench to stop it turning and use a spanner or second wrench to tighten the nut. You will be able to ‘feel’ when the joint is tight so don’t overdo it.
Open the water supply again and inspect your work.
There are several reasons why a push-fit fitting may be leaking and you will need to do a little investigation to determine what’s wrong. If the pipe is not fully located into the connection and sitting fully against the internal stop, it may be possible to stop the leak by pushing the pipe in fully. Otherwise, you will need to drain down this section of pipework.
Dismantle the joint – this will either be using the special key tool or by pushing the collet towards the fitting, depending on the type used. Inspect the pipe end for damage. On plastic pipe, there will be a metal pipe insert which should sit cleanly and squarely inside the pipe end. If the pipe end is not square this may be the problem. Check both the securing ring and O ring seal for any signs of damage. Do not put your fingers into the fitting – they can be extremely sharp. If there is damage, use a new fitting making sure to keep it clean in the process. Dirt and debris in this type of fitting can easily cause the joint to fail.