Who is responsible for blocked drains in London?

London residents can still be very confused regarding who is responsible for unblocking or repairing drains on their property. I have even come across drainage engineers from other companies who get themselves in a muddle.

Why is it important to know?

If the problem drains are your responsibility, then you must arrange for a London drainage contractor to unblock the drain and any carry out repairs.

However, if the drain is the responsibility of Thames Water (for customers in London), they are obliged to clear the blocked drain FREE of charge.

Drain responsibility in London explained

This diagram explains how the general rules for the responsibility of drains in London works for different types of property including terraced houses, semi-detached and detached houses or for blocks of flats and apartments.

Blocked drain responsibility in London

The guiding rule is if a drain is shared or not on your property, then it is not your responsibility. This applies to all of London, so it doesn’t matter if you are in Kensington, Croydon, Finchley or Whitechapel, the same rule applies.

Semi-detached and terraced houses

If a drain on your property is shared with a neighbour, then Thames Water are responsible for it, even if it is in your garden. You are ONLY responsible for the drains on your property that are not shared with a neighbour.

Detached houses

Assuming a detached property in London has no shared drains, then the homeowner is responsible for the drains up to the property boundary, and Thames Water is responsible for all blockages or repairs off your property.

Blocks of flats

Thames Water consider a block of flats in London as a single property. The flat owner or tenant is usually responsible for drains within the flat. The freeholder or management company is then responsible for the drains up to the property boundary and Thames Water for all the drains beyond that.

What is a lateral drain?

A lateral drain is a section of a private drain (not yet shared) that lies off your property (see the home on the far-right of the diagram above) and either connect to a neighbour’s drain or connects directly to a public sewer.

Lateral drains in London are since 2011, the responsibility of Thames Water.

What’s the difference between a drain and a sewer?

A drain is a pipe that serves a single property whereas a sewer serves more than one property. All drains lead to a sewer or a sewage treatment plant.

It wasn’t always this way

Before 2011, there used to be different rules for properties built before and after 1937. Those London properties built pre-1937 would receive more help with their drains from Thames Water, than those built after 1937.

The government decided that this was unfair and too complicated, so in 2011, the law was changed so that any drainage in London that was either shared or off your property, was now the responsibility of Thames Water.

Still unsure if you have a shared drain?

The first port of call for householders or business owners in London for advice about drain ownership is Thames Water, www.thameswater.co.uk.

Thames Water has sewer plans for all of London, but not all of them are accurate or yet up to date. Even in one street in Wandsworth, Chiswick or Hampstead, there may be numerous different drain/sewer layouts.

If you are still unsure about the ownership of drains in your home, please ask. We have many years of experience of working with London’s drain.

Please call 0800 3579 365 or email info@imperialdrainage.co.uk for advice.