How to Unblock a Blocked Kitchen Sink — 6 Methods That Work

Stagnant dishwater in the kitchen sink is not just a bad sight (and smell!).

It’s also unhygienic.

Read on to learn how to tackle this common problem.

What causes a sink blockage 

 There are three common causes of blocked kitchen sinks:

• Fats, oils, and grease (FOG): Don’t pour these down the drain when they are hot. When they cool, they can solidify onto the pipes. 
• Soap scum: When soap comes into contact with minerals in your tap water, it leaves behind soap scum. This builds up in your pipes and can trap food debris.
• Food debris

It’s a mix of more than one and the build up happens gradually over time. Sometimes you can tell there’s a building by the bad smell from your kitchen sink (even before water has stopped flowing through it). 

Wider issues

Some blockages are caused by wide issues, such as outside pipe blockages/damage or incorrect sink installations. These are often difficult to diagnose without the help of a professional. However, some signs you can look out for are: 

• Recurring blockages or slow draining of sinks
• Multiple sinks in your home being blocked at once
• Toilers not flushing or making gurgling sounds
• Strong sewage smells nearby outside drains. 

If you notice any of these, get in touch with a professional plumber. (Or, your home cover provider, like YourRepair!).

Initial signs of a blockage: a slowed down sink

First, you should determine if the flow of water in your sink has slowed down or stopped entirely.

If the water is moving slowly, this suggests a build-up of debris in your pipes. 

This can often be fixed using one of the following methods.

Boiling water 

This is a simple and inexpensive way to unclog your sink drain. If the blockage is caused by oil or grease, the heat will help to ease it away. 

Boil a full kettle and slowly pour all the water down the drain. Be careful not to splash yourself. 

Only do this once or twice though. Most UK kitchen sinks have PVC pipes and rubber seals which will be damaged by repeated pouring of boiling water.

Baking soda (bicarbonate of soda) & vinegar 

Allow the sink to drain as much as possible and then pour half a cup of baking soda down the drain (bicarbonate of soda, not baking powder). 

Follow this with a cup of vinegar. 

The mixture will fizz up. Leave it to sit for at least 30 minutes and then flush the pipe with hot water from the kettle. 

This might clean out any debris and also help to neutralise bad smells. 

However, take note: although some homeowners swear by this method (some even use it to unblock toilets without plungers), many plumbers believe it’s unreliable! 

Chemical plughole unblockers 

Most supermarket cleaning sections and hardware shops have chemical sink unblocking products. 

These are not suitable if your sink is filled with water.They only work if you are able to get at least some liquid into your plughole, i.e., if it’s draining slowly and not totally blocked.

Follow the instructions on the packaging to unblock your plughole. Most will guide you through something along the lines of: 

• Pour into the plug
• Wait 5 - 10 minutes
• Turn the tap on gently/slowly to see if the blockage has gone.

A completely blocked sink

Plungers 

If the water is not moving at all, you may need to reach for the plunger to get the water flowing again. 

Plungers need a sink full of water to create a seal. Position the plunger over the plughole and push straight down a few times. 

Remove the plunger and see if the water has started to drain. Do this a few times to try to push the blockage down the drain.

Drain hair clog remover

If you cannot unblock your kitchen sink with a plunger, try using a drain hair clog remover.

This flexible, and relatively cheap piece of plastic has small barbs. The barbs are designed to latch on to blockages and allow you to pull them back up the drain.

Once you’ve inserted it into the plughole, it should be able to work its way around the U-bend easily. 

When you reach the blockage, try to dislodge it. Leaving water in the sink as you do this will show you if the blockage has shifted as it starts to drain.

After removing the blockage, try one of the methods above to clear any remaining debris from the pipes. 

Undo the U-bend

First, clear the space under your sink and place a washing up bowl underneath its U-bend.

Next, wearing kitchen gloves, undo the U-bend by turning the nuts on both sides anticlockwise.

Once the U-bend is fully loosened, previously blocked water may rush out and into the washing up bowl.

Now, use your (gloved) hands to push out whatever is blocking the U-bend (into the bowl).

Once this is done, put the U-bend back on (turn the nuts clockwise) but keep the bowl there. 

Run the tap to double check the U-bend is on properly. If it is, the job is done.