How to unblock a sink

Likely causes

Food scraps, grease, soap scum and toothpaste build up in traps and waste pipes. A blockage confined to one sink often sits in the bottle trap or the first metres of waste. If several fittings are slow, the problem may be further along the drain.

Steps that usually help

1. Put on gloves. Place a bowl under the trap.
2. Try a sink plunger with enough water to cover the cup; seal the overflow with a wet cloth on basins.
3. If plunging fails, undo the bottle trap, empty it into the bowl, and clear debris.
4. Check the short waste into the wall or floor for obstruction before refitting washers and hand-tightening the trap.
5. Run hot (not boiling, on plastic pipes) water to flush residual grease after the flow returns.

Safety notes

• Avoid mixing different chemical cleaners.
• Caustic products can splash and damage fittings — mechanical clearing is preferable.
• Do not use metal wire carelessly on plastic traps; you can puncture them.

When to call a professional

If the trap is clear but water still backs up, or foul smells continue, book blocked sink, bath and shower or blocked drains clearance. For toilets, see how to unblock a toilet. Call 01332 314146 when sewage risks entering the home.