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Who is Responsible?

Drains and Sewers


There are different names for the pipes commonly used to discharge waste water from buildings. In order to establish who is responsible when the pipework becomes blocked or needs repair it is necessary to understand the different types.

Drainage Responsibility

Internal PlumbingAbove ground plumbing and pipework prior to entering a private or shared drain, including rain gutters and soil pipes.Property owner
Private DrainA drainage pipe serving one property within your property boundary.Property owner
Shared Private DrainA drainage pipe serving multiple properties at one location, for example, blocks of flats, caravan or park home sites, industrial/business/retail parks, school/university campuses, and hospital/medical facilities.

Property owner/s

Lateral DrainA private or shared drain outside of the property boundaryThames Water
Private SewerA drainage pipe which serves two or more propertiesThames Water
Public SewerThe drainage pipe into which a private drain discharges directly or via a private sewerThames Water

The following diagrams aim to show you the distinction between the responsibilities of property owners and Thames Water.  The green pipe is the responsibility of the property owner, while the pink pipe is the responsibility of Thames Water.

Detached house  Semi-detached  
Detached Property      Semi-Detached Property

Terraced  Flats  
Terraced Property       Flats

(Source: Thames Water)

If you think you have a problem with a sewer pipe or drain, please carry out the following steps as it's important that you try and identify where the problem is and will save you unnecessary callouts, which you may be charged for.

  • If you have a shared sewer, try asking your neighbours if they have a problem. If they do not, it's possible that the problem is on the section of pipe or waste plumbing you are responsible for.
  • If your neighbours do have a problem, it may be on a shared section of pipe and Thames Water will be responsible.

For issues affecting solely your own property we do not provide recommendations for drainage companies; we would advise that you consult the phone directory for a local business.  Thames Water can be contacted on 0800 316 9800 (Textphone: 0800 316 9800), 24 hours a day

Thames Water: Online Enquiry Form
 - for non-urgent queries you can use the

Privately-owned Septic Tanks, Cess Pits and Biodiscs and their connecting pipework, large multi-occupier commercial sites, and sewers that carry water directly to a watercourse remain the responsibility of those who derive benefit from it.