How to unblock a kitchen sink

Inspired by Mr DIY — Craig Phillips. This guide draws on the "How to unblock a sink" video from Craig Phillips, one of the UK's best-known DIY presenters, whose channel covers practical home maintenance in a no-nonsense style. The walkthrough shows both the quick methods and the proper U-bend clean-out for more stubborn blockages.

1. Try the simplest thing first

Before anything else, remove the plug strainer and pull out any visible food debris or hair by hand. Unpleasant, but often the whole problem. Run hot water and see if the drain clears.

If it is still slow, pour a kettle of just-boiled water directly into the drain. This softens and shifts fat that has congealed in the pipe. Follow it with a squeeze of washing-up liquid and more hot water. For a mild blockage, this is often enough.

2. Use washing soda and boiling water

Washing soda (sodium carbonate) is more aggressive than bicarbonate of soda and far better at cutting through kitchen grease. Put about half a cup down the drain, follow it with a full kettle of boiling water, and leave it for ten minutes.

This method works well for partially blocked drains where water is draining slowly but not completely stopped. Repeat it once if the first attempt improves but does not fully clear the drain.

3. Try a plunger

If the chemical approach has not fully fixed it, use a cup plunger — not a toilet plunger. Fill the sink with an inch or two of water so the plunger cup seals against the drain. Cover the overflow hole with a wet cloth to stop the pressure escaping.

Plunge firmly about ten times, then remove the plunger and see if the water drains. The blockage may shift on the first attempt or it may take several rounds. If there is a second bowl in the sink, plug that too before you start.

4. Use a chemical drain cleaner

If plunging has not worked, a gel drain cleaner is the next step. These products work by dissolving the organic matter causing the blockage. Follow the instructions on the packet carefully — most require a 30-minute to overnight dwell time.

Do not use chemical drain cleaners if you have already poured bleach or vinegar down the drain — the combination can create fumes. And never use them in a fully blocked sink where the water has nowhere to go.

5. Clean out the U-bend

If nothing above has worked, the blockage is almost certainly sitting in the U-bend itself and needs to be physically removed. Put a bucket under the trap before you start — there will be water in it.

Unscrew the plastic slip nuts on either side of the U-bend by hand, or use a pair of grips if they are tight. Pull the trap away, empty it into the bucket, and clear out any solid matter. Rinse it under a tap and refit, hand-tightening the slip nuts. Do not overtighten plastic fittings — snug is enough.

6. Check the rest of the pipe run

If the U-bend was clean and the sink is still blocked, the obstruction is further down the waste pipe. A flexible drain rod or drain snake can reach further into the system. Feed it gently into the pipe and work it back and forth to break up or retrieve the blockage.

That said, if you have reached this point, it may be quicker to call in help. A blockage in the soil stack or outside drain is a different job.

When to call a handyman

Call Richard if the drain is completely solid and none of the above methods have moved it, if multiple sinks or drains in the house are blocked at once (which suggests a problem further down the system), or if the U-bend has cracked or is leaking after the clean-out. Some blockages are just too stubborn or too far down to tackle from above.