First, limit the damage
Put a bowl under the leak and move anything stored there. If water is coming from a supply pipe and you can’t stop it, turn off the water at the stopcock — our guide shows how to find and turn off your stopcock.
Find the source
Dry everything with a towel, then run the tap and watch. Dab suspect joints with tissue — a damp patch shows exactly where the water is coming from. Check whether it only leaks when the tap runs, which points to the tap or supply, or when water goes down the plughole, which points to the waste pipe.
Common causes
A loose or worn waste connection under the basin is the most frequent. Flexible tap connectors and isolation valves can also weep at their joints. A cracked or corroded pipe will keep leaking, and a worn seal around the tap or sink can let water run down behind. If you have a dishwasher or washing machine connected, check its supply and waste connections too.
What you can safely try
Tighten a loose nut gently by hand or with a light turn of a spanner — overtightening can crack the fitting. If a washer or seal looks worn, replacing it is a simple fix for many people.
When to call a plumber
Call a plumber if you can’t find the source, if a pipe is corroded or cracked, if the leak keeps coming back, or if water has reached electrics. A slow leak left alone can rot the cabinet and cause damp — see signs of a hidden water leak. For a sudden gush, follow what to do with a burst pipe.
Leak under the sink? Our Gas Safe plumbers cover South Manchester and Cheshire.
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