How to Fix a Leaking Pipe Under the Sink

Overview

A leaking pipe under the sink can cause water damage and mould. This guide covers fixing a leaking pipe joint.

Step-by-Step Fix

1. Locate the stopcock or isolation valve for your sink's water supply, typically found on the pipework directly beneath the sink or sometimes further along the cold water feed. Turn this valve fully clockwise until the water flow completely stops to prevent further leakage and ensure safety before starting any repairs.
2. Position an empty bucket or a sturdy container directly underneath the leaking pipe joint to catch any water that may still drip out after turning off the supply. You may also want to lay down some old towels or newspaper to protect the cupboard base from any splashes.
3. Thoroughly dry the leaking joint and the surrounding pipework with a cloth or kitchen roll so you can clearly see where the leak is originating. Once dry, gently try to move the compression nut by hand to see if it feels loose as this is often the cause of minor drips.
4. If the nut is loose, carefully tighten the compression nut using an adjustable spanner or a suitably sized wrench, turning it clockwise by a quarter to half a turn at a time. Do not overtighten, as this can damage the pipe or the olive, but ensure it feels snug and secure.
5. If tightening the nut hasn't stopped the leak, you will need to replace the olive, which is the small brass ring inside the joint that creates the seal. First, fully undo the compression nut and slide it back, then carefully wiggle the pipe free from the fitting to expose the old olive.
6. Once the old olive is removed and a new one is in place on the pipe, wrap 3-4 layers of PTFE (Polytetrafluoroethylene) tape clockwise around the olive, ensuring it sits flat and neatly. This will provide an extra layer of sealant and help create a watertight connection when the joint is reassembled.
7. Slowly turn the water supply back on by rotating the stopcock or isolation valve anti-clockwise until fully open. Carefully inspect the repaired joint for any signs of dripping or seepage, and also check nearby connections to ensure no new leaks have been inadvertently caused.

Common Symptoms & Diagnostic Resolutions

Review the common error codes and operating symptoms below to quickly identify the root cause of the fault before ordering replacement parts.

Frequently Asked Questions