Help & Advice
Know your house drainage system
Learning more about the layout of your home drainage system beyond the sink can be extremely helpful. After all, these pipes play an essential role in taking water and wastewater to and from the various appliances you rely on daily, so it’s worth knowing how they work.
In this guide, we will discuss the basic functions of the pipes that take wastewater away from your home. These pipes are at risk of being clogged and, therefore, require care and attention to keep them running smoothly.
The typical house drainage layout is a complex pipe network
This image shows that a blockage created in one area can potentially impact the entire home, depending on where the problem occurs within the drainage system.
U-bends and blockages
If you look under your bathroom or kitchen sink, you should see a U-bend pipe (although these are occasionally contained within a pedestal or other covering). The U-bend is there to collect water and stop foul-smelling gases from escaping into the home. It’s also a common spot for blockages to form, often caused by an accumulation of food, hair or soap scum.
Depending on the appliance, the U-bend and other wastewater pipes are not typically very large, measuring around 32mm in diameter. As such, even a small amount of solid material can create a blockage very quickly. This is why property owners are advised to be vigilant about preventing non-degradable items and substances such as fats, grease, wet wipes and nappies from entering these pipes.
If your U-bend is blocked, find out ways to unblock it in our article ‘How to unblock a sink by yourself’.
The pipe shut-off
Should you have a clean water leak, blockage or other problem, knowing where to find the shut-off valve for your house’s water supply can save you a lot of time and trouble, especially if you’re dealing with overflowing water.
In some houses, you should be able to turn the water supply off for individual appliances, using the correct shut-off valve next to it.
If your home isn’t set up this way, you can also turn the water off for your whole house. This shut-off valve will usually be somewhere on the outside edge of your home, so making a note of its location for future reference is a worthwhile precaution.
Finding the drain
After a little investigation, you should be able to find the main drain connecting your house to the sewer pipe.
There will most likely be a drain cover somewhere outside your home within your boundaries that indicates where this is. It can be useful to know this information, should you need to identify where a blockage in your system is; the location of manhole chambers is also something that’s essential to consider if you’re planning to extend your property.
Bear in mind that these covers are heavy, and harmful gases can lurk inside, so make sure the necessary care and precautions are taken when opening them. If you suspect there’s a problem, it’s usually better to call a professional rather than trying to tackle this on your own. Untrained professionals should never enter the drains themselves.
FAQs
Once you’ve learned the basics of how your piping system works, it’s likely that you’ll have a few follow-up queries about how they operate, and how they might need to be looked after when things go wrong. Here are answers to a few frequently asked questions
The network of pipes taking water away from your home will connect to a main sewer pipe that will serve other homes around you. Under rules set out in 2011 via the Private Drains and Sewers Act, you’re responsible as a homeowner for the sections of piping that sit within your home’s boundaries. Once the pipe leaves the boundaries of your home, it becomes the responsibility of your water or sewage company.
This is because the 2011 legislation transferred ownership of most of the private sewers in England and Wales to the utilities companies, except pipes that exclusively serve a private property. However, there are still a few drains that work on a shared ownership model between several properties, so if you want to learn more about how these responsibilities are decided, read our article ‘What are private drains and sewers?’.
Should you have a blockage or other issue in a pipe that’s within the boundaries, it’ll be up to you to fix it, which is why it’s useful to know more about how they work.
If your home was built after 1920, it is likely that your property has two separate drains: a foul sewer drain and a surface water sewer drain. This ensures that rainwater can be funnelled directly into a local waterway, while wastewater is taken to the sewage works for processing.
It is estimated that around 500,000 UK properties have misconnections, meaning foul water is erroneously connected to the surface water drain, resulting in pollution to rivers and beaches.
For more information on the difference between surface water drains and foul water drains, read our article ‘Can surface water drain to a foul sewer?’.
As the homeowner, you are legally responsible for correcting this issue, so it’s important to make sure you’re able to recognise possible indicators that your property might be at risk.
These include:
- A new manhole within your property, as this means the drainage has been altered
- New bathrooms, toilets or kitchens added as part of an extension, or water-based appliances installed in garages or other outbuildings, as these often result in misconnections
- Pipes connected to the downpipes from your roof guttering
Find out more information about your responsibilities in our article ‘Blocked sewer drains: Who is responsible?’.
In most cases, surface water, which is simply rainwater that runs off your property’s roof and paved areas, is collected by drains and gullies that flow into a public sewer. Because local utility companies operate these sewers, most people are charged for the cost of surface water drainage through their sewerage bills.
However, if no rainwater drains from your property into the public sewer system because you have a soakaway – or if all the surface water from your home drains directly into a watercourse, brook or stream – you don’t have to pay this charge. If you think you’ve been paying for this service in error, then you can apply for a rebate and have money knocked off your regular bill.
To find out whether you may be eligible, then get in touch with your local water company and investigate further – it’s possible that you could be due a significant saving.
There are many reasons why a property owner or resident might need to find out where their drains run. For example, you may be planning an extension, or you may need this information to carry out essential repairs to your pipes.
To obtain these plans, you have several potential options:
Contacting your local water authority or regional council – please note that these organisations will usually charge an administration fee to provide the necessary information.
Making use of the free-to-use LSBUD service, which can provide schematics on request for hundreds of thousands of kilometres of underground and overhead pipelines and cables across the UK
Getting in touch with the previous property owner, who may have already obtained the drainage plans and can pass them along to you
If you are looking for a more detailed view of how your drain or sewer line runs, it may also be possible to organise a CCTV survey, allowing you to find out more about the layout and condition of your drains.
If you’d like a detailed plan of the utilities infrastructure of your property, services such as free-to-use Line search before U dig can provide schematics on request.
For more information about your plumbing system, sewer arrangements, and drainage responsibilities, you can also contact your local water and wastewater services supplier directly.
- Anglian Water (supplies East Anglia and the East Midlands)
- Dŵr Cymru/Welsh Water (supplies most of Wales)
- Northern Ireland Water (supplies Northern Ireland)
- Northumbrian Water (supplies the north-east of England)
- Scottish Water (supplies Scotland)
- Severn Trent Water (supplies central England and parts of Wales)
- South West Water (supplies Devon and Cornwall, and parts of Dorset and Somerset)
- Southern Water (supplies Kent, Sussex, Hampshire and the Isle of Wight)
- Thames Water (supplies London and parts of central southern England)
- United Utilities (supplies the north-west of England)
- Wessex Water (supplies the south-west of England)
- Yorkshire Water (supplies Yorkshire)