Drain shared with the neighbours: who’s responsible?
It is one of the most common conversations with homeowners:
- “The problem is in the pipe at the front, but we only use the back bathroom.”
- “It is the neighbour’s fat, not ours.”
- “That drain runs through our land, but it is not ours… is it?”
When a drain is shared between properties, things get tricky, not because the pipe is complicated, but because the rules are not always clear. Let us clear that up.
What is a shared drain?
A shared drain is any stretch of pipe that takes wastewater from two or more homes and carries it into the public sewer.
It does not matter whose garden it runs through, who built their extension first, or whether your house is detached, semi, or a converted flat. If the drain takes more than one household’s waste, it is considered shared, and that makes a big difference in who is responsible.
Who is responsible for shared drains?
In most cases, your local water authority is responsible. Since October 2011, the law changed, and shared private drains became the water board’s responsibility, right up to the connection with the main sewer.
If a blockage or break happens in the shared section, you can usually report it to your water company, and they will send someone out.
What are you still responsible for?
- The pipework within your boundary, before it connects to a shared drain
- Internal plumbing (toilets, sinks, showers)
- Any new additions or modifications, such as if you have built over a pipe or re-routed a drain incorrectly
If a problem is in your section only, you will need to sort it out yourself or call someone like ASL Limited.
Common problems with shared drains
- Backups after heavy rain – If the shared pipe is slow or blocked, water might come back up into your home, especially if you are at the lower end of the system.
- Neighbour disagreements – It is not always easy to agree on who caused the problem, especially with things like wet wipes, fat, or tree roots.
- Extension complications – Building over a shared drain without permission can cause major issues, both during construction and when repairs are needed later.
What we recommend
- Get a CCTV survey if you are unsure who is responsible. It can trace the pipe and show who it serves.
- Do not just dig. Shared drains often need permission or notice to the water authority before any work can be done.
- Speak to your neighbours early. If the issue affects them too, it is usually best to tackle it together. You may not have to pay at all.
When to call ASL Limited
- Find out who is responsible
- Identify the exact problem
- Avoid unnecessary digging or costs
- Deal with water board cases where needed
Click this link about blocked drains.
You do not have to get stuck in a neighbour dispute, and you definitely do not need to feel lost trying to decode pipework under the lawn. ASL Limited has been solving these issues for decades.
Suspect a shared drain issue?
📞 Call ASL Limited on 0800 181 684. The guesswork will be taken out of it for you.
We cover Surrey, Berkshire, Hampshire, West Sussex and South West London.
