In short
Who pays to clear a blocked drain depends on where the blockage sits, because the owner changes along the pipe. Pipework inside your boundary that serves only your home is generally your job. The public sewer network is Thames Water's, and so are most shared pipes that used to be private, following the nationwide transfer in 2011.
If you are not sure which side your problem falls on, send a request online. A local engineer can then check the drain, because the answer is not obvious from above.
The symptoms of an outside drain problem
An outside problem looks different from an internal blockage. Watch for these signs, since they show where to look:
- An overflowing gully, which is the small grated drain outside the kitchen backing up.
- A surcharging manhole, where water bubbles up through an inspection cover, sometimes with a smell.
- Several fixtures backing up at once, such as the sink, the bath and the gully on the same day.
- Neighbours with the same problem, which strongly suggests a shared pipe.
If several fixtures fail together, the cause is likely downstream of your home. It is therefore probably in a shared or public section, not in one internal pipe.
Where the boundary sits
The line between yours and theirs is not always where people expect. Three terms make it clear, however:
- A private drain carries waste water from one property to the point where it joins a shared pipe or the public sewer. You usually look after it.
- A lateral drain is the pipe that continues from your boundary, often under a neighbour's garden or the road, to the public sewer.
- The public sewer is the network that Thames Water owns and maintains.
The 2011 private sewer transfer
Before October 2011, most lateral drains and many shared sewers belonged jointly to the households that used them. A blocked pipe under someone else's garden could mean a shared and disputed bill. However, national rules then moved most private sewers and lateral drains in England and Wales to the water companies.
Banbury sits in Thames Water's area. Most pipework from your boundary out to the public sewer is now theirs to maintain, even where it was once private. That helps homeowners, since a blockage that once meant haggling with a neighbour is now usually the water company's job.
There are exceptions. Pipework that serves only your home, entirely within your boundary, generally stays yours. Some newer estates also have unusual layouts. As a result, it is worth checking the actual drain rather than assuming.
Shared and lateral drains explained
A shared drain serves more than one property before it reaches the public sewer. These are common on older Banbury streets around Grimsbury and Neithrop, where houses were built close together. Since October 2011, most shared drains are Thames Water's from the point where they join a pipe serving another property, even inside your boundary. A pipe serving only your home stays yours up to your boundary.
The difficulty is that you cannot see from the surface where your drain ends. A camera inspection traces the route and shows where the blockage sits against your boundary. That is often the quickest way to settle the question, since guessing from above rarely works. Our guide to what a CCTV drain survey costs explains what affects the price.
What to do right now
If a gully is overflowing or a manhole is surcharging today, act quickly. Take these steps in order, because each one narrows the cause.
- Stop adding water to the system. Avoid taps, the washing machine and extra flushing until it clears.
- Check whether neighbours are affected. If several homes on the street share the problem, it points to a shared or public sewer.
- Look at where the problem sits. A blockage between your house and the boundary is more likely yours, while one beyond it is more likely shared or public.
- Get it checked properly. Our blocked drains service can find exactly where the problem is, and advise whether to clear it or report it to Thames Water.
For gullies, manholes and private pipes in your garden, our external drain unblocking service covers the work. However, if sewage reaches your home, follow our advice on first steps in a drain emergency.
Local help
We deal with outside drains across the area, since tracing a run shows where it changes hands. See our pages on blocked drain help in Chipping Norton and drain repairs in Bicester. We also cover drain unblocking in Southam and emergency plumbing in Woodstock.
In town, our Banbury service area page lists everything we cover, while pages for nearby towns follow the same layout.
Related guides
Start with the symptoms of a blocked drain if you are still unsure. For the practical steps, read outdoor drain clearing. Homes off the mains are different, so see the General Binding Rules and how often a septic tank needs emptying.
If you are buying a house, a drain survey for home buyers can show who owns which pipe. A burst water pipe is a separate matter, covered in what to do about a burst pipe.
Frequently asked questions
Is a blocked drain my responsibility?
It depends where the blockage is. Pipework within your boundary that serves only your home is generally yours to maintain. However, once the drain joins a pipe serving another property, it is usually Thames Water's job after the 2011 transfer, even inside your boundary.
Who fixes a shared drain?
Most shared and lateral drains in the Thames Water area passed to the water company in 2011. Blockages in those sections are generally reported to and cleared by Thames Water, not split between households. If you are unsure, an engineer can trace the drain and confirm.
Sort it out properly
Working out whose drain it is from the surface is often guesswork. Therefore, the only reliable way is to trace the run and find the blockage. Request help online and we will identify where the problem sits, and advise whether to clear it ourselves or point you to Thames Water.
