How to unblock a sink
Most blocked kitchen and bathroom sinks can be cleared without harsh chemicals. Work through these methods in order, from the simplest to clearing out the U-bend.
- Time
- 15 to 45 minutes
- Difficulty
- Easy
- Cost
- Low cost
- Steps
- 6
- Checked
What you’ll need
- Sink plunger (cup-shaped) Search Amazon for sink plunger
- Rubber gloves Search Amazon for household rubber gloves
- Bucket or washing-up bowl
- Damp cloth to block the overflow
- Bicarbonate of soda and white vinegar (optional)
- Plastic drain unblocking stick (optional) Search Amazon for drain unblocker stick
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Safety first
- If you have already used a chemical drain unblocker, don't plunge or open the trap: the chemical can splash onto your skin or into your eyes. Follow the product's instructions and flush well first.
- Never mix different drain cleaners or mix them with bleach. Dangerous fumes can form.
- Wear gloves when opening a trap. The water inside is dirty.
Step by step
-
Step 1: Clear the plughole
Put on gloves. Scoop out standing water into a bucket if the sink is full. Remove the plug or pop-up stopper if it lifts out, and pull out any hair, food or soap scum you can reach. Run the tap briefly: sometimes this is all it takes.
Next: step 2 -
Step 2: Use a plunger
Block the overflow hole with a damp cloth, otherwise the plunger just pushes air out of it. (On a double kitchen sink, block the other plughole too.) Leave a few centimetres of water in the sink, put the plunger squarely over the plughole and pump firmly up and down a dozen or so times, then lift it off sharply. Repeat a few times.
Next: step 3 -
Step 3: Try hot water and washing-up liquid for grease
Kitchen sinks are usually blocked by fat and food. Squirt some washing-up liquid down the plughole and follow it with a kettle of hot water, poured slowly. Don't use boiling water on plastic pipes or ceramic sinks if your manufacturer advises against it.
Next: step 4 -
Step 4: Try bicarbonate of soda and vinegar
Pour a few spoonfuls of bicarbonate of soda down the plughole, then a cup of white vinegar. Let it fizz for 10 to 15 minutes, then flush with hot water. It works best on mild blockages.
Next: step 5 -
Step 5: Clean out the U-bend (trap)
If the water still won't drain, the blockage is probably in the trap under the sink. Put a bucket underneath, then unscrew the trap by hand (the large plastic nuts usually turn anticlockwise). Tip out the water and clear the gunk, rinse it and screw it back together, making sure the rubber washers are seated. Run the tap and check for leaks.
Next: step 6 -
Step 6: Go further down the pipe
If the trap was clear, the blockage is further along. A cheap plastic drain stick or a hand-held drain auger (snake) can reach a metre or so into the waste pipe.
Tips
- Put a strainer in the plughole to catch hair and food scraps.
- Never pour cooking fat or oil down the sink. Let it cool in a jar or pot and put it in the bin. Water companies say fat is a major cause of blocked pipes and sewers.
- Pour a kettle of hot water and a squirt of washing-up liquid down the kitchen sink every week or so to help stop grease building up.
When to call a professional
Call a plumber or drainage company if several drains are slow at once, water comes up in another sink or the bath, or there's a bad smell outside. That points to a blockage in the main drain. If the blockage is in a shared sewer or public drain, contact your water company.
Questions people ask
Does bicarbonate of soda and vinegar really work?
It can help with light build-up, but it won't shift a solid blockage. A plunger or clearing the trap is more reliable.
Can I use bleach to unblock a sink?
Bleach cleans and disinfects but doesn't break down grease or hair. Never mix it with other drain products.
Why does my sink smell?
Food and grease build up in the trap. Clean the trap and flush with hot water and washing-up liquid.
Sources
Checked 9 October 2026. We wrote this guide in our own words, using:
- Mansfield District Council: how to unblock a sink (tenant guide) (mansfield.gov.uk)
- Thames Water: Bin it, don't block it (thameswater.co.uk)
- Ideal Home: how to unblock a sink (idealhome.co.uk)
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Printed from howtoguides.uk/guides/how-to-unblock-a-sink/ · Checked 9 October 2026 · General information only. For gas, electrics, structural work, medical, legal or money decisions, use a qualified professional.