How to unblock a drain safely depends on what is causing the blockage. A slow-draining sink, unpleasant smells, gurgling sounds or standing water can all be signs that a blockage is developing.
The good news is that many minor blockages can be dealt with using a few simple methods before you need professional help.
In this guide, we’ll explain 5 proven ways to unblock a drain, what you should avoid doing, how to prevent future blockages and when it is time to call a professional plumber in London.
The good news is that many minor blockages can be dealt with using a few simple methods before you need professional help.
In this guide, we’ll explain 5 proven ways to unblock a drain, what you should avoid doing, how to prevent future blockages and when it is time to call a professional plumber in London.
What Causes a Blocked Drain?
Drain blockages can happen for several reasons, depending on which part of your plumbing system is affected.
Common causes include:
- Hair and soap build-up in bathroom drains
- Food waste and grease in kitchen sinks
- Fat, oil and grease entering the pipework
- Wet wipes and sanitary products being flushed down toilets
- Foreign objects falling into sinks, showers or toilets
- A build-up of debris inside older pipes
- Blockages in external drains or underground drainage pipes
Kitchen drains are particularly vulnerable to grease and food waste, while bathroom drains commonly become blocked because of hair and soap residue. Thames Water’s guidance on blockages also highlights fat, oil, food scraps, wet wipes, and sanitary items as common causes of blockages.
If you notice that several drains in your property are becoming slow at the same time, the problem may be further down the drainage system rather than in one individual sink or shower.
How to Unblock a Drain: 5 Proven Methods
1. Try Hot Water First
If you have a slow-draining kitchen sink, hot water may help loosen grease, soap and other light deposits inside the pipe.
Start by removing any standing water from the sink if possible. Pour hot water slowly down the drain and wait several minutes before checking whether the water is flowing more freely.
This method is most effective for minor blockages caused by grease or a light build-up. It is unlikely to solve a completely blocked drain caused by a solid obstruction.
Avoid repeatedly pouring extremely hot water into plumbing if you are unsure what type of pipework or fittings you have.
2. Use a Plunger
A plunger is one of the simplest tools for dealing with a minor blocked drain.
It works by creating pressure inside the pipe, which can help loosen the material causing the blockage.
To use a plunger:
- Put enough water into the sink, bath or basin to cover the rubber part of the plunger.
- Place the plunger firmly over the drain.
- Make sure you have a good seal around the opening.
- Pump the plunger up and down several times.
- Remove the plunger and check whether the water begins to drain.
- Repeat the process if necessary.
If you are using a plunger on a sink with an overflow opening, covering the overflow with a damp cloth can help create a better seal.
A plunger is particularly useful for minor blockages in sinks, baths, showers and toilets.
If repeated attempts do not improve the drainage, avoid applying excessive force. The blockage may be further down the pipe.
3. Clean the Sink Trap
If your kitchen or bathroom sink is blocked, the obstruction may be sitting inside the trap underneath the sink.
The trap can collect food debris, grease, hair and other material over time.
Before removing it, place a bucket underneath the pipe because water trapped inside the plumbing will usually come out when the connection is opened.
Carefully remove the trap, clean out any visible debris and then reassemble it securely.
Once everything is back in place, run the tap slowly and check carefully for leaks.
If the connections are difficult to remove or appear damaged, don’t force them. Breaking a connection underneath the sink can turn a simple blockage into a water leak.
4. Use a Drain Snake
If the blockage is deeper inside the pipe, a drain snake or drain auger may be able to reach it.
A drain snake is a flexible cable that can be pushed into the pipe until it reaches the obstruction. Carefully rotating the cable can help break up or retrieve the material causing the blockage.
When using one:
- Insert the cable slowly into the drain.
- Continue until you feel resistance.
- Rotate the cable carefully.
- Avoid forcing it if it becomes stuck.
- Try to loosen or retrieve the blockage.
- Remove the cable and check the drainage.
- Flush the pipe with water if the blockage has cleared.
Drain snakes can be useful for hair, soap deposits and other relatively accessible blockages.
If the cable cannot reach the blockage or you suspect a damaged pipe, professional equipment may be required.
5. Check the External Drain
Sometimes the problem isn’t inside your sink or bathroom at all.
If several fixtures in your home are draining slowly at the same time, there could be a blockage further along the drainage system.
You may notice:
- Several slow-draining fixtures
- Gurgling sounds from drains
- A strong sewage smell
- Water collecting around an external drain
- Wastewater backing up
- Problems affecting more than one property
If there is an accessible external drain, you can look for obvious signs of a blockage from a safe position.
However, never enter a manhole or attempt to work inside a deep sewer. Drainage systems can contain dangerous gases and other hazards.
If you suspect a serious external or underground blockage, contact the appropriate professional service.
What You Should NOT Do When Your Drain Is Blocked
Not every popular drain-unblocking trick is a good idea.
Don’t Mix Drain Chemicals
Never mix different drain-cleaning products.
Combining chemicals can create dangerous reactions and harmful fumes.
If you have already used a chemical drain cleaner, tell the plumber before they start working on the pipe.
Don’t Keep Flushing a Blocked Toilet
If your toilet is blocked, repeatedly flushing it can cause wastewater to overflow.
Stop using the toilet until the blockage has been cleared.
Don’t Flush Wet Wipes
Wet wipes are a common cause of drainage problems.
Even products labelled as flushable can contribute to blockages in drainage systems.
Thames Water’s advice on what to flush is simple: only pee, poo and toilet paper should be flushed, while items such as wet wipes and sanitary products should go in the bin.
Don’t Pour Cooking Oil Down the Sink
Cooking oil, fat and grease can accumulate inside pipework and contribute to blockages.
Instead of pouring them down the sink, allow them to cool and dispose of them appropriately.
Thames Water recommends putting fats, oils and grease in the bin rather than allowing them to enter your drains.
When Should You Call a Plumber?
A minor, isolated blockage can often be worth attempting to clear yourself.
However, you should consider professional help if:
- The blockage keeps coming back
- Several drains are blocked
- Wastewater is backing up
- There is sewage around an external drain
- You notice a strong sewage smell
- A blockage appears to be underground
- A plunger has not worked
- A drain snake has not worked
- You suspect a damaged or collapsed pipe
- Water is starting to flood your property
A recurring blockage should not simply be treated over and over again. It may indicate a deeper problem somewhere in the drainage system.
If your blocked drain needs professional attention, plumbing services in London can help identify the cause of the problem and determine the most appropriate solution.
Is a Blocked Drain Your Responsibility?
For London homeowners and tenants, it is useful to understand that not every drainage problem is necessarily the property owner’s responsibility.
Responsibility can depend on where the blockage is located and whether the pipe serves one property or several properties.
Generally, private drains serving a property are normally the responsibility of the property owner or landlord up to the point where they connect to the public sewer.
Ofwat’s guidance on responsibility for sewers and drains explains that household drains and private sewers are normally the responsibility of the householder or landlord up to the point where they connect with public sewers.
If you live in a property supplied by Thames Water and believe the problem may be in the public sewer, you can report the issue to Thames Water for investigation.
Thames Water’s guidance on sewer pipe responsibility explains that homeowners are generally responsible for waste drainage pipes within their property boundary when they serve only that property, while Thames Water is responsible for public sewers and shared sewers.
If the blockage is inside your property or in private pipework serving only your home, you may need a qualified plumber instead.
How to Prevent Blocked Drains
Prevention is usually much easier and cheaper than dealing with a serious blockage.
Keep Food Waste Out of Kitchen Drains
Use a sink strainer to catch food particles and avoid putting cooking oil, fat and grease down the sink.
Scrape food waste into the bin before washing plates and pans.
Thames Water’s advice on preventing blockages recommends putting fats, oils, grease and food leftovers in the bin instead of down the drain.
Keep Hair Out of Bathroom Drains
Hair can quickly combine with soap and other deposits to create a stubborn blockage.
A simple drain cover or hair catcher can help reduce the amount of hair entering the pipe.
Be Careful What You Flush
Your toilet should not be treated like a waste bin.
Avoid flushing:
- Wet wipes
- Sanitary products
- Cotton buds
- Paper towels
- Nappies
- Other household waste
Thames Water recommends only flushing the three Ps — pee, poo and toilet paper — and putting other household waste in the bin.
Clean Drains Regularly
Regularly removing hair, soap residue and other visible debris can help prevent a minor build-up from becoming a major blockage.
Blocked Drain in London? Start With the Right Solution
A blocked drain doesn’t always mean you need an expensive repair.
For a minor blockage, you can start with simple methods such as hot water, a plunger, cleaning the sink trap or using a suitable drain snake.
However, if the blockage keeps returning, affects several fixtures, causes wastewater to back up or appears to be outside your property, professional investigation is usually the safer option.
Understanding where the blockage is located can also help you determine whether you should contact a plumber, your landlord or the local sewerage company.
If you need help with other plumbing or property-related problems, Homacord property maintenance services in London can provide a broader solution for your home.
Need Help With a Blocked Drain in London?
If you’ve tried the basic methods and your drain is still blocked, continuing to force the blockage could make the problem worse.
A professional plumber can investigate the cause of the blockage and determine whether the problem is limited to one fixture or is part of a larger drainage issue.
For professional help with blocked drains and other plumbing problems, Plumbing Services London can provide the assistance you need.
Homacord provides plumbing and property maintenance services for homes across London.
If you need help with a blocked drain or another plumbing problem, contact Homacord to arrange professional assistance.
Frequently Asked Questions
What is the quickest way to unblock a drain?
For a minor blockage, using a plunger is usually one of the first methods worth trying. Hot water may also help with some grease-related kitchen sink blockages.
How can I unblock a drain without chemicals?
You can try a plunger, clean the sink trap or use a suitable drain snake. These methods can often be attempted without using chemical drain cleaners.
Why is my drain still blocked after using a plunger?
The blockage may be further down the pipe, too large to move with a plunger, or caused by a damaged section of pipe. If the problem keeps returning, professional investigation may be necessary.
Why are several drains blocked at the same time?
Several blocked or slow-draining fixtures can indicate a blockage further down the drainage system rather than a problem with one individual sink or shower.
Who is responsible for a blocked drain in a rented property?
It depends on the location and cause of the blockage, as well as the terms of the tenancy. Private drainage serving the property and public sewers can have different responsibilities.
Ofwat’s guidance on responsibility for sewers and drains provides further information about the responsibilities of property owners, landlords and sewerage companies.
Should I call Thames Water for a blocked drain?
If you suspect the problem is in a public sewer or affects multiple properties, contacting Thames Water may be appropriate. If the blockage is inside your property or in private pipework serving only your home, you may need a plumber.
Thames Water’s blocked drains guidance explains how to identify where a blockage may be located and who may be responsible for dealing with it.
Can I use drain cleaner to unblock a drain?
Chemical drain cleaners should be used cautiously. Never mix different products, and always follow the manufacturer’s instructions. For a stubborn or recurring blockage, professional investigation may be a safer option.
