How to unblock a drain

What you'll need

Step-by-step guide

1. Identify the blockage location
   Is it one sink or all drains slow? If one sink is slow, the blockage is local — in the trap or just beyond it. If all drains are slow, the blockage is further down the main drain.
2. Try the hot water method first
   Boil a kettle. Pour it slowly down the drain in three stages, waiting 30 seconds between each pour. For kitchen sinks, this dissolves grease blockages surprisingly often.
3. Use baking soda and vinegar
   Pour half a cup of baking soda down the drain, then half a cup of white vinegar. The fizzing reaction breaks up organic blockages. Cover the drain for 15 minutes, then flush with hot water.
4. Use a plunger
   Fill the sink with enough water to cover the plunger cup. Place the plunger over the drain and plunge vigorously — 15-20 pumps. The pressure dislodges the blockage. Pull the plunger away sharply on the final stroke.
5. Clear the trap manually
   Under the sink is a U-shaped pipe (the trap). Place a bucket underneath, unscrew the trap by hand or with a wrench, and clean it out. Most blockages are here. Clean it, check for damage, and refit.
6. Use drain rods for outdoor drains
   For outdoor inspection chambers, use drain rods — screw sections together, insert into the drain, and rotate clockwise as you push. Never rotate anticlockwise as the rods will unscrew underground.

Expert tips for the best result

• Never mix chemical drain cleaners with other products — the reaction can be dangerous
• A weekly hot water flush prevents most kitchen blockages from forming
• Fit drain hair catchers in bath and shower — they cost £3 and save hours of unblocking
• Chemical drain cleaners work but damage pipes with regular use — use them only as a last resort
• Outdoor blocked drains are often a shared responsibility between neighbours — check if it's on your side first