If a drain serves only your property, it is your responsibility. If it serves more than one property, Thames Water is responsible. That single rule, updated by the October 2011 private sewer transfer, resolves the majority of London drain disputes — but the boundary between private and shared is not always where you expect it to be.
The Basic Rule: Private vs. Public
The key distinction is between private drains and public sewers:
- Private drain: The pipes that drain water from your property exclusively. Your responsibility to maintain and repair.
- Public sewer: Pipes that drain water from more than one property, or that are vested in Thames Water. Thames Water's responsibility.
For most London terraced houses, your responsibility ends at the boundary of your property — or sometimes at the junction where your drain connects to the shared system. That said, it is rarely that simple in practice.
The 2011 Change: Private Sewers Transfer
In October 2011, the UK government transferred responsibility for private sewers (those serving more than one property) and lateral drains from homeowners to the water companies. This was a major change that affected millions of London properties. As a result, hundreds of thousands of households who used to face shared-drain repair bills are now legally entitled to free Thames Water repairs.
Before 2011, if your house shared a drain with your neighbour, you were jointly responsible for maintaining it — often leading to expensive disputes about who should pay for repairs. However, after October 2011, Thames Water took over responsibility for these shared private sewers.
In addition, this transfer only applies to lateral drains running outside your property boundary and to sewers shared by two or more properties. Therefore, the section of drain running within your property boundary remains your responsibility. According to Thames Water's published guidance, many homeowners who paid for shared drain repairs since 2011 may be entitled to a refund.
Mapping Your Drainage
To understand exactly where your responsibility ends, you need a drainage plan. Thames Water provides a free sewer records service — you can request your property's drainage records online or call 0800 316 9800. This shows the mapped position of public sewers relative to your property.
However, sewer records are not always accurate, especially in older London properties where drainage has been modified over the decades. Therefore, if you are buying a London property, a CCTV drain survey combined with a drainage search is the most reliable way to understand the drainage layout and identify any defects before you exchange contracts.
When Thames Water Won't Act
Thames Water is obliged to deal with problems in public sewers and adopted lateral drains, but they can be slow to respond to non-emergency issues. Reporting a blockage to Thames Water typically involves:
- Reporting online or calling 0800 316 9800
- Thames Water scheduling an inspection (which can take several days)
- Thames Water determining whether the problem is on public or private pipework
- Thames Water scheduling remedial works if required
This process can take weeks for non-emergency issues. Many London homeowners choose to hire a private drain company to resolve blockages immediately, then seek to recover costs from Thames Water if the fault turns out to be in adopted pipework.
Practical Advice
Keep a written record of any drain problems you report to Thames Water, including dates and reference numbers. If Thames Water delays unreasonably in attending to a problem in their pipework, you may be entitled to compensation under the Guaranteed Standards Scheme.
For drain problems clearly on your private pipework, acting quickly is always the right approach. Blocked drains that are left to worsen can cause internal flooding, structural damage from water ingress, and subsidence from undermined foundations — all of which are far more expensive than the original blockage.
Frequently Asked Questions
Who is responsible for the drain between my house and next door?
Since October 2011, drains serving more than one property are Thames Water's responsibility. If the blockage is in the shared section, call Thames Water first on 0800 316 9800.
Thames Water says the blockage is on my side. How do I verify this?
Request that they share the CCTV footage and adoption boundary information. If you disagree with their assessment, we can conduct an independent CCTV survey and produce a report showing the exact location of the blockage relative to the adoption boundary.
I paid to fix a shared drain since 2011. Can I get a refund?
If the drain has since been confirmed as adopted by Thames Water (shared, serving more than one property), you may be able to claim. Contact Thames Water directly or consult a drainage solicitor.
Does my home insurance cover drain blockages?
Some home insurance policies include drain cover, typically for private drains only. Check your policy documents for "drain" or "underground services" cover. Many policies require a CCTV report to process a claim.
How quickly can you attend an emergency drain blockage in London?
We cover all 32 London boroughs with a typical 60-90 minute response, 24 hours a day, 365 days a year. Call 0204 593 7845 for immediate help.