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How to Unblock a Sink

By: Jack Claridge - Updated: 30 Apr 2018 | comments*Discuss
Blocked Sink Kitchen Sink U Bend

At one time or another as a DIY novice or expert you may well be called upon to unblock a sink in the kitchen or the bathroom.

The most common sink to be unblocked is the kitchen sink and this is simply because foodstuffs inadvertently make their way down through the plughole and can gather.

Both the sinks and toilet in your home are attached to what is referred to as the ‘foul water drain’; a drain which as it name might suggest takes waste water and waste products away from the home and into the main sewage system.

The U Bend

Most commonly blockages in sinks occur in what is known as the ‘U Bend’ – the same name is used to refer to the drainage pipe attached to the rear of your toilet. Given the shape of the ‘U Bend’ and the fact that sometimes larger pieces of debris do not float or can become trapped in the base of this pipe, this is where most of the blockages will occur and this is where you should start.

Blocked Sinks

The first thing you will notice when it comes to a blocked sink is that the water may still continue to drain but will take longer to do so. If you notice this problem occur or it is brought to your attention it is best to act sooner rather than later. Likewise blocked sinks will fill with water when there is no plug in the plughole.

If you have children in the household it is best to educate them as to what not to put down the plughole. Many DIY enthusiasts have found themselves removing cotton buds, cotton wool, disposable kitchen towels and all manner of other things including – as we have already mentioned – foodstuffs.


The first way in which to establish if you have a blockage that cannot be easily removed is to try and plunge the plughole. Plunging is simply a case of removing and adding air to the pipe in order to dislodge anything that might be down there.

First of all try placing the palm of your hand over the plughole and pumping up and down a few times to see if the water level begins to drop. Of course this is a rudimentary manner in which to plunge the sink but it can work. There are also the old fashioned sink plungers – the suction cup on the end of a stick – which work just as well. By placing the suction cup over the plughole and cutting off the air and then pumping it up and down this too can dislodge any item that is small enough to be moved by the current.

With DIY now becoming one of the fasted growing leisure pursuits there are always new gadgets coming onto the market and the latest is what is known as the ‘blast plunger’. This is effectively a pump which covers over the plughole as you might do with your hand or an old fashioned plunger but you force air in and out using a pump handle.

Removing the U Bend

You may find that not everything is as easily dislodged as we have described above so you will have to undo the ‘U Bend’. To do this you should have the following items to hand:

  • Bucket
  • Waterproof Tape
  • Plunger (if necessary)
  • Screwdriver
  • Towel or cloth

You will notice that the ‘U Bend’ has two sets of threads – one directly underneath the sink and one further along where the bend finishes. Unscrew the first set of threads – underneath the sink and then slowly and gently pull it free. You should at this point place the bucket and towel underneath the sink to catch any water or debris that may be stuck. Then undo the second set of threads – to be found at the end of the bend. This will allow you to remove this section of pipe which is in the shape of the letter ‘U’. If there is a blockage it will most likely be in this section of pipe and you can use a screwdriver or piece of flexible wire to clear out the inside.

Once you are satisfied that the blockage has been cleared replace the pipe, screwing the threads tightly shut – but not too tightly or they may crack. Use a few strips of waterproof tape to seal around the edges just to ensure there are no excess drips and then plunge the sink again.

After you have completed this procedure you should find the sink is blockage free.

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[Add a Comment]
just unblocked my sink after reading comments, did not have a wire coat hanger just used a bit of wiring from an old electric appliance, did the job. thank you.
shevvy - 24-Oct-17 @ 12:33 PM
I have a blocked kitchen sink since yesterday! The whole kitchen was flooded because the water from the washing machine goes down that drain as well! We managed to clear it this morning with a plunger and the water went out fine! I just turned a washing machine on again and in the last 15 min of the washing machine going, the sink was blocked again! What can I do? Should I use the plunger again? Or put baking soda and vinegar down? Does malt vinegar would work as well? Or only white vinegar? It would be great if you could help me?
Heike - 9-Apr-17 @ 4:22 PM
Hi there - boy am i glad i found this site - my toilet has been blocked for three days and i did not know what to do - so i looked online and found this helpline - it worked within minutes - i used the mop with the carrier over it and all is well now - i cannot thank you enough for the information - peace and blessings to you.
Piglet - 2-Apr-17 @ 2:06 PM
I have a modern bathroom washbasin – the type that has a push down ceramic plug in the middle. It's blocked and I can't work out how to get the plug out so that I can use a plunger to force through whatever's blocking it. To make matters worse, we've recently had a water meter fitted and the water pressure is now about 50% stronger (not sure how that helps the environment, but definitely costs double) – so our pipes now make a deep buzzing sound when two taps are on in the house, and they don't drain so quickly and appear blocked regularly. Help would be greatly appreciated.
Tim - 4-Sep-16 @ 11:40 AM
pet - Your Question:
My Kitchen sink was Blocked, I unblocked with different brand of unblocker still the same becoming worst. what will I do, please advice.

Our Response:
Have you removed the U'bend? As specified in the article you may find that not everything is as easily dislodged as we have described above so you will have to undo the ‘U Bend’. If this does not help, then you will invariably have to call a plumber.
DIYBasics - 20-Nov-15 @ 2:09 PM
My Kitchen sinkwas Blocked, I unblocked with different brand of unblocker still the same becoming worst. what will I do, please advice.
pet - 20-Nov-15 @ 5:04 AM
I poured hot water down the drain. It was sweet.
hot water - 9-Aug-15 @ 8:01 PM
@Daniel - glad they are of help Daniel.
DIYBasics - 22-Jun-15 @ 10:31 AM
Drain Clogging is a common issue for everyone. Your post gives useful information on sink drainage unblocking. Find your tips very helpful.
Daniel Leyland - 19-Jun-15 @ 6:23 AM
@Fosterette - the article explains what you can do under these circumstances. If you have tried all of the above and nothing has happened, then I'm afraid it is time to call a plumber.
DIYBasics - 19-May-15 @ 11:09 AM
Hi, I leave with 8 other girls in a student residence. And we've got a big problem : our sink is blocked and it's full of water. What can we do? Thanks for the answers!
Fosterette - 15-May-15 @ 12:06 PM
Want to open ubend but it's too locked , what do I use to loosen the threads? Oil, hot water? Thanks
Emmet - 15-Nov-14 @ 10:21 AM
Thanks!Just given my u-bend a good going over and sink is draining better than ever before!
RNM - 28-Sep-14 @ 2:53 PM
My sink as been blocked for ages thank you
riley - 20-Jul-14 @ 7:56 PM
Awesome, just what i needed. Had a blocked sink for like two weeks now, and think this would be a great idea. Thank you :)
Nic - 16-Sep-12 @ 9:02 PM
There are powders and liquids you can put down the sink to clear a blockage. Depending on what’s blocking it though, they might not work too well. If a plunger doesn’t do the job, a straightened wire coat hanger pushed down can sometime be exactly what’s needed without taking things apart.
Lewis - 11-Sep-12 @ 2:27 PM
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