Drains and sewers

Blockages or defects to drainage is either the responsibility of the local sewerage undertaker (Thames Water) or the owner of the property that the drainage serves.

The distinction for responsibility lies with the location of the drain or sewer. This is explained in full detail below the image, which shows how drains and sewers are connected to different types of residential properties.

Diagram showing drains and sewers and how they connect to different types of residential properties

A drain is a single pipe serving one premises

A drain is an underground pipe, usually 4" in diameter, which carries either surface water or foul water from a single property. It will usually discharge into a public sewer. Usually the house owner is responsible for their drain until it leaves the boundary of the associated property. Beyond the boundary, the sewerage undertaker (Thames Water) is responsible.

A sewer is a drain that serves more than one premises

A sewer is an underground pipe which carries the surface water or foul water from more than one property. This may be on private or public land. The local sewerage undertaker (Thames Water) is responsible.

A lateral drain

This is a drain that is outside the private boundary of the property it serves and may be on public land or adjoining private land. The local sewerage undertaker (Thames Water) is responsible.

Road gullies/drains

These collect surface water from the roads (as opposed to foul water/sewage from properties). The council deals with blocked highway drains and road gullies that are causing surface water flooding – this should be reported via the online form below. 

Report a drain or sewer problem

Blockages and defects

From time to time drains and sewers, both private and public become blocked. There are many reasons why blockages occur.

The following are some of the more usual:

  • Build up of fat in the pipe
  • Foreign matter causing obstructions (often baby wipes, nappies & sanitary wear)
  • Poor design
  • Tree roots
  • Inadequate fall or pipe size
  • Defective section of pipe or joint

When a blockage occurs in a drain serving one house, only one property will be affected.

If a blockage occurs in a sewer, usually the first property affected is the one immediately upstream of the blockage because this is where the sewage will start to overflow. However all properties upstream of the blockage will eventually be affected as their waste water will not be able to flow away satisfactorily.

What should I do if I suspect a blockage (foul/waste not flowing away as usual)? 

Speak to your neighbours and try to find out who is affected.

If you suspect it is only you, (ie: the blockage is in your drain), it is the responsibility of the house owner/holder, which may be you or your landlord. Facilitate the clearance by arranging for a drainage clearing company or contact your landlord/letting agent (tenants may be responsible depending on the tenancy agreement and the cause of the blockage). 

If more than one property is affected, contact the statutory undertaker Thames Water who is responsible.

Because of the obvious health risks, if action is not taken by the owners the Local Authority may need to get the matter resolved and may take formal action. If no action is taken as a result of a formal notice, we will arrange for the clearance and the costs will be charged those responsible. Please note there will also be an administration charge.

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