How to Unblock a Sink

Planning & preparation

• A blocked sink is a common problem that tends to be caused by a build-up of everyday debris and food getting caught in the pipe below the sink
• A blockage can usually be fixed with a plunger, a product such as a blaster cup, plumber’s snake or a chemical drain cleaner. However, if a larger object has become wedged in the pipe then you’ll need to remove the blockage manually
• Several methods for unblocking a sink are shown in this guide, but if your problem persists then call in a professional

Do it right

• Dispose of waste from the U-bend or strainer into a bin rather than flushing back down the sink
• When plunging or using a blaster cup, always block the overflow with a wet cloth to ensure an airtight seal
• If you’re using a chemical drain cleaner, try and choose one that is eco-friendly and biodegradable, and always follow the manufacturer’s directions for use

Staying safe

• Turn off the water supply before carrying out any plumbing work
• Wear gloves if using a chemical drain cleaner and always follow the safety recommendations on the packaging of any product used

Aftercare

• Carefully disposing of cooking oil and ground coffee will help keep your sinks clear. Fitting a drain grate or screen will also help to keep things flowing
• Regular maintenance includes flushing the sink with hot water, occasionally using a heaped teaspoon of baking soda sprinkled into the plughole, or a cup of white vinegar poured down the plug hole and left for around 30 minutes
• Use of an eco-friendly drain liquid can help prevent blockages, but always check all manufacturer's instructions
• Store manufacturer’s instructions for your sink and tap somewhere safe, as this information could help you to solve the problem as quickly as possible

How to remove small blockages

Step 1

Place a plunger or blaster cup over the plug hole. Then, block the overflow with a wet cloth to create an airtight seal.

Step 2

Gently pump the plunger or blaster cup up and down whilst keeping the overflow firmly covered. This should be enough to dislodge small blockages.

Step 3

If this fails to clear the blockage, then try using a liquid drain cleaner. Be sure to wear protective gloves while using this product.

Step 4

Pour the liquid down the plughole, as per manufacturer's instructions, and a fizzing reaction will occur as the debris is broken down.

Step 5

Repeat a few times and then rinse through with warm water.

Step 6

If the blockage persists, try using a plumber’s snake. To use, carefully push the snake down the drain whilst twisting to help it get around the U-bend.

Step 7

Once you reach the obstruction, pull, twist and push the plumbers snake until the blockage is removed. Then rinse through with cold water.

How to remove large blockages

Step 1

If none of these methods have worked it’s time to deal with the plumbing directly. Start by identifying the first bend in the pipe underneath the sink; this is a U-bend called the ‘trap’.

Step 2

Turn the water supply off by turning the stopcock clockwise.

Step 3

Place a bucket or watertight container underneath the trap to catch any water that spills out.

Step 4

Unscrew the two compression fittings that hold the trap in place. You may need to use a wrench if the compression fittings are especially tight.

Step 5

Carefully remove the trap and empty the water into the bucket or container below.

Step 6

Take a look inside the trap and remove any debris that has built up using a piece of stiff wire. Throw the waste from the pipe in the bin to avoid further problems.

Step 7

Once the trap has been unblocked, secure it back into position underneath the sink.

Step 8

Turn the water supply back on by turning the stopcock anti-clockwise.