Kitchen sink blocked or draining slowly

Kitchen sink blockages are almost always caused by a build-up of cooking fat, grease, food debris, and washing up liquid that solidifies inside the waste pipe over time. Hot grease poured down the drain solidifies as it cools, progressively narrowing the pipe.

Start with a plunger: put on rubber gloves, block the overflow hole with a damp cloth (so the plunging pressure goes down the drain rather than out the overflow), and plunge vigorously 10–15 times. Run hot water and check if draining improves.

If plunging does not clear it: pour half a cup of bicarbonate of soda into the drain, followed by half a cup of white vinegar. Cover the drain and leave for 30 minutes. Follow with a full kettle of just-boiled water. The fizzing reaction helps cut through grease.

If still blocked: place a bucket under the U-bend (the curved trap under the sink). Unscrew the trap — most modern ones have hand-tight plastic connections. Empty and clean the trap thoroughly. The blockage is often entirely within the trap itself.

If clearing the trap does not resolve it, the blockage is further down the drain run. A flexible drain rod or sink snake (£10–£15 from a DIY store) can probe further into the pipe. Insert it and rotate clockwise while pushing to break up the debris.

To prevent future blockages: never pour cooking fat or oil down the drain — let it solidify in a container and dispose of it in the bin. Pour boiling water down the drain weekly and use a sink strainer basket to catch food debris.