Guide
Blocked drains outside: who is responsible, you or the water company?
Updated
The costliest drainage mistake is paying a private firm for the water company's blockage. The line moved in 2011; many householders and some drain firms still get it wrong.
The 2011 transfer, in one paragraph
On 1 October 2011, most private sewers and lateral drains in England and Wales transferred to the water and sewerage companies. That was under the Water Industry (Schemes for Adoption of Private Sewers) Regulations 2011 (legislation.gov.uk).
Before that, neighbours could be jointly liable for a shared pipe none of them knew they owned. Now the rule of thumb is simple. You own the drain serving only your property, inside your boundary; almost everything else is the water company's.
The three pipes, defined
- Drain
- The pipe serving only your property, inside your boundary. Yours. You pay to unblock and repair it.
- Lateral drain
- The continuation of your drain beyond your property boundary, before it joins a sewer. The water company's since 2011, even though only your property uses it.
- Sewer
- Any pipe serving two or more properties, including a shared pipe running through private gardens. The water company's, wherever it runs.
How to work out which one is blocked
- Is more than one property affected? If your neighbour's gully is backing up too, the blockage is almost certainly in a shared sewer. Water company's job.
- Lift the manhole covers you can reach safely. A chamber full of water means the blockage is downstream of it; a dry chamber means upstream. If the last chamber inside your boundary is dry, the problem is likely in the lateral drain, water company again.
- Only your property, only inside your boundary? Then it is your drain and your bill. That is the moment to get prices, not before.
What this means in practice
- Call your water company first when there is any chance the blockage is shared or beyond your boundary. They clear blockages in public sewers and lateral drains at no charge to you.
- Renting? Drains inside the property are normally the landlord's repairing responsibility, not the tenant's. Report it; don't book and pay yourself.
- Exceptions exist. Some properties were never connected to public sewers (septic tanks, private pumping arrangements) and some pre-1937 arrangements differ. If ownership is genuinely unclear, the water company can tell you what its records show.
A private firm that finds the fault in a public sewer should tell you to stop and call the water company. The good ones do. If your problem might sit near the boundary, say so when you ask for prices. An honest engineer would rather tell you on the phone than charge for a wasted visit.