A pipe usually leaks at a joint because the seal inside the fitting has worn, moved or was not made properly in the first place. Movement in the pipework, changes in temperature, corrosion and damaged seals are the most common reasons a joint starts to drip.
Joints are where two pieces of pipe meet, so they are naturally the weakest points in most plumbing. The type of joint can help explain why it is leaking.
Different Joints, Different Weak Spots
Compression fittings use a nut and a small brass or copper ring, called an olive, to grip the pipe. If the nut loosens or the olive is damaged, water can seep out around the nut. These are common under sinks and on pipes that feed taps and valves.
Push-fit fittings rely on rubber seals and grip rings. They can leak if the pipe was not pushed fully home, was cut at an angle, or has been pulled or twisted since it was fitted.
Soldered joints on copper pipe are made with heat. A joint that was not fully sealed, or that has corroded over time, may weep slowly and leave a green or white crust behind.
Why a Joint That Was Fine Starts to Leak
Pipes expand and shrink a little as hot and cold water run through them. Over time, this small movement can loosen a joint. Pipes that are not clipped firmly can move even more, especially when a tap is turned off quickly.
Seals also age. Rubber can harden and crack, and metal parts can corrode. Recent work nearby, such as fitting a new kitchen or moving a washing machine, can knock a joint just enough to start a leak.
Why Tightening It Yourself Can Backfire
It can be tempting to grab a spanner and tighten the nut. Over-tightening can crush the olive or crack the fitting, turning a slow drip into a bigger leak. Taking a pressurised fitting apart is not a safe DIY job either.
A safer step is to place a bowl or towel under the joint, keep the area dry, and turn off the water at the stop tap or a nearby isolation valve if the drip is getting worse. Do not force a valve that is stiff or will not move.
What a Proper Repair Looks Like
A plumber will usually check what type of joint it is and why it failed. Sometimes a new olive or seal is enough. In other cases the joint needs to be remade or a short section of pipe replaced, especially if the pipe end is damaged or corroded.
If you have a joint that keeps weeping, our leaking pipe repair service in Oxford can look at the fitting and the pipe around it. Mention the type of pipe and where the joint is when you get in touch, as it helps the plumber come prepared.