Why is my kitchen sink overflowing?

Why is my kitchen sink overflowing?

Your kitchen sink system is designed to use gravity, so dirty water is drained away from the sink and into the pipes and drains.

So it can be a worry when water starts coming back up through the plug hole and into the kitchen sink. It’s usually a sign of a problem with your drainage and there’s most likely a blockage at some point in the system.

So why is the water coming back up the kitchen sink?

There are a number of reasons including:

Kitchen sink blockages

Debris and food scraps from washing plates and cleaning vegetables can block the kitchen sink plug, pipework, and siphons underneath.

Problems with kitchen sink overflow

Kitchen sink overflow holes need regular cleaning. Old or worn-out overflow pipes and fittings might need replacing.

Clogged drains

Food scraps, grease, fat, and oil can solidify and cause blockages in the drainage pipe. Properly dispose of them in the bin rather than pouring them down the sink.

Appliance drainage

Sometimes, a number of fixtures use the same pipe, especially in the kitchen. So water from the washing machine or dishwasher could be the root of the problem.

It might be that the blockage is coming from a different pipe but backing up into your sink.

Plumbing vent issues

A clogged vent pipe can disrupt the proper air pressure in your plumbing system, leading to slow draining sinks.

The pressure imbalance might cause water to back up and overflow into your kitchen sink.

Contact a plumber near you who can get to the bottom of why your kitchen sink is overflowing.

What is a kitchen sink overflow?

The overflow on a kitchen sink is a small opening at the back or side of the sink, underneath the taps and just below the rim.

It’s connected around the back of the sink to an overflow pipe that leads down into the drain.

A kitchen sink overflow stops your sink from overspilling and flooding if someone accidentally leaves the tap running when the plug is in.

It diverts excess water into the overflow pipe and on to the main drain.

How do you unblock a kitchen sink overflow?

Your kitchen sink overflow must be clear of dirt and other debris to make sure the water flows freely to the overflow pipe and drain.

That’s why cleaning around your overflow hole regularly is important to prevent a build-up of grime, grease and dirt.

Is your kitchen sink overflow clogged? Then follow these simple steps:

• You’ll need boiling water, a funnel and a pipe cleaner or brush
• Alternatively make a DIY cleaning solution by mixing a teaspoon of baking soda and half a cup of vinegar
• Clean the overflow hole by pushing the brush in and around to remove dirt, stains and a build-up of grease
• Get the funnel and stick it in the overflow hole
• Slowly pour boiling water (or your cleaning mixture) into the funnel to flush the dirt and build up
• Repeat the process until the overflow hole is clean
• Remember to wear protective gloves to prevent splashing the boiling water on your hands

If your overflow pipe gets blocked, your kitchen sink may overflow. However, a blockage is highly unlikely in this part of the sink as there’s usually a guard over the opening.

It’s more likely to be that the overflow pipe is developing normal wear and tear, such as a worn-out washer or a faulty pipe.

In this case, you’ll see dripping into the cabinet underneath the sink.

Ways to unblock an overflowing sink

The best way to unblock an overflowing sink that’s not draining properly will depend on the cause of the problem, as the various unblocking methods work differently.

We recommend contacting a plumber to get to the root of the problem quickly.

Here are a few methods to try yourself:

1. Use the waste disposal (if you have one)

This might seem obvious, but if you have a waste disposal unit built into your sink, then it should be your first step in trying to clear your sink. A build-up at the bottom of a disposal unit can sometimes cause a small blockage in the system if you haven’t used it in a while.

Run the waste disposal and check that it works properly. If the sink is still not draining, you’ll need to try another method.

2. Pour boiling water down the sink

Boiling water is a quick, easy, inexpensive solution that clears some sinks. That’s why it’s the best one to try first.

Boiling water may be all your pipes need to loosen a blockage caused by a build-up of fats, soap residue and food debris.

First, remove as much standing water as possible from the sink. Then, slowly pour boiling water into the plug hole and wait.

Let it sit for a few minutes, then run the hot top to clear the pipes. You may need to repeat this process several times to remove the blockage.

If this process doesn’t work, it’s time to move on to the next method

3. Baking soda and vinegar solution

You can create a homemade unblocking solution using baking soda and vinegar. Before pouring the solution down the sink, make sure you’ve cleared any standing water from the sink so that the solution can get to work on the blockage in the pipes.

First, pour a cup of baking soda down the drain, followed by a cup of vinegar and then put the rubber plug stopper in. The solution should then fizz and push the clog down the drain, hopefully clearing it. After a few minutes, pour hot water down the drain to clear out the solution.

4. Baking soda and salt mixture

Another homemade remedy to help clear a sink drain is to mix a cup of baking soda with a cup of salt and pour it down the drain. Leave it for a few hours to break down any blockages clogging the pipes, and then rinse with hot water to flush out any debris.

5. Use a plunger

Plungers can often be a very effective way of clearing a kitchen sink that’s not draining – especially if you have a lot of standing water in the sink that you can’t get rid of.

Cover the whole drain hole with the plunger and plunge several times until you notice the water suddenly recede and drain away.

Is the sink still not draining correctly after multiple plunging attempts? Time to try a different method.

6. Check the P-trap

The sink’s U-bend is the curved bit of the drainpipe underneath your sink. A P-trap is your U-bend plus another bit of piping that together resembles a ‘P’ shape.

Sometimes, food debris and grease collect in the U-bend and turn into gunk, causing your sink to drain slowly or not at all.

To check and clear your P-trap first, turn the water supply off to the sink, then unthread the slip nuts.

When removing the drain pipe, get a bucket ready to catch any water or debris. A wrench or Channellock pliers can help with tricky nuts.

Pull the trap to remove it, then clean the pipe before reinstalling it.

7. Insert a pipe snake

Persistent blockages that prevent your sink from draining might need to be physically unblocked using a pipe snake.

A pipe snake is a thin, flexible cable that you can insert down the drain. It will bend with the shape of the pipe and break up any stubborn blockages. Once inserted into the drain, it’s helpful to move the pipe snake up and down to help properly break up any clogs—then flush the drain with hot water.

8. Sink unblocking products

Last but not least, you can try a sink unblocking product from your local supermarket or hardware store. They can be pretty effective at unblocking sinks.

Follow the manufacturer’s instructions on the label and always finish by flushing the drain with hot water afterwards.

If your kitchen sink continues to block and overflow after you’ve tried all of these steps, get in touch with a local plumber who can help fix the issue.

How to prevent future blockages

To avoid your kitchen sink from overflowing, there are some simple tips to make sure your sink is draining correctly.

The key is to dispose of items correctly and get into good sink habits.

Here’s how to prevent future blockages:

• Collect grease, fats and oils in an old tin and once full and sealed, put it in the general waste bin
• You can also recycle used cooking oil
• Put coffee grounds, egg shells and starchy foods in a food waste bin or compost them
• Don’t pour paint away into a sink. Liquid paint is banned from landfill too
• Recycle kitchen roll or food wrappers
• Run hot water down the drain after each sink use
• Pour any leftover boiled water from the kettle down the plughole to kill off bacteria
• Pour baking soda down your drain once a week

FAQs

Why is my kitchen sink not draining?

A blocked or poorly draining kitchen sink can be a real nuisance, so if you find your sink draining slowly, it’s time to fix it.

The top reasons for your kitchen sink not draining are:

• Food waste blockages
• Food wrapping and other plastics stuck in the pipes
• Build up of butter, fats or soap scum
• Damaged pipes

Why is water coming out of my kitchen sink overflow?

You might have a clog or obstruction in your drain pipe. In that case, follow the steps above to clear a kitchen sink blockage, then allow the sink to drain off.

If this doesn’t work, the culprit might be a clogged main drain line, which can prevent water from draining properly and lead to a backup and overflow.

How do I know if my kitchen drain is blocked?

If your kitchen sink is overflowing and takes ages to drain, you may be dealing with a blocked kitchen drain.

You might also be experiencing an unpleasant sewage smell in your home or hear gurgling noises.

You can take steps to solve the problem, such as removing leaves and debris from a blocked drain.

When should I hire a professional plumber?

We recommend hiring a plumber as soon as you notice your drainage is not working as it should.

A plumber can unblock the drains inside your home and determine why your kitchen sink is overflowing. They will perform an inspection and likely use a plunger, drain rodding, or chemical products. They might also disassemble pipes to remove blockages at the source.

If your outside drains are blocked, you may need to hire a drain clearance specialist to solve the problem.

How much does it cost to unblock an overflowing kitchen sink?

The average cost of hiring a plumber to come and fix your blocked sink is around £45 per hour, depending on the complexity of the job and the individual plumber.

If your blocked sink is part of a bigger problem in your kitchen, you might need to install a new kitchen sink and taps.

The average cost to install a kitchen sink and taps is £572.50.