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Designing your sewer connection

Before you apply for a sewer connection, you’ll need to understand your requirements.

The different types of sewers

Most of the sewers in our network are called public sewers – these are designed to collect the flow of sewage or rainwater from properties. There are other categories of sewer, such as trunk or chemical sewers.

Which type of sewer do I need to discharge to?

  • Foul water sewers carry wastewater from appliances such as toilets, baths, showers, sinks, dishwashers, washing machines, etc
  • Surface water sewers carry surface water, usually rainwater, from rooftops, roads, driveways and paved or hardstanding areas
  • Combined sewers carry both foul water and surface water, only applicable in certain circumstances
  • Trade effluent sewers carry wastewater from industrial trade premises

Finding the location of sewer

There are several ways to find the location of a sewer:

  1. If you can find a nearby manhole, this will give you an idea of where the sewer is. If you don’t want to connect at this point, you can ask a contractor to lift the cover and check which way it runs to find the next connection point. You may be able to do it yourself but do take care as manhole covers can be heavy.
  2. Sewer records are freely available to view at your local authority offices.
  3. Sewer and utility maps are available to purchase from several property search providers, including Thames Water Property Searches.
  4. A drainage specialist can provide you with extensive advice on how to locate a sewer.

Confirming ownership - direct or indirect connections

There are two different types of connections to a public sewer:

  • Direct connections – your connection is made directly to a public sewer which usually owned and looked after by Thames Water.
  • Indirect connections – your connection is made to a private drain, which then discharges to a public sewer. You’ll need permission from the owner of the private drain to connect, as well as Thames Water.

Moving a manhole

If you have a public manhole in your property that you wish to move, known as a manhole relocation, please apply online.

Designing your proposed connections

You’ll need to submit drawings showing the following details of your proposed connection or relocation:

  • Detailed drainage plan (scale 1:100 – 1:500) showing your entire site. Including:
  • All buildings & roadways
  • Location and direction of flow of all private sewers/drainage
  • The proposed connection point to the public sewer
  • View an example drawing
  • Site location plan (scale 1:500 – 1:1250) showing your site boundary within the surrounding area

You can prepare these yourself or ask a drainage consultant to do this. See our connection terms and conditions for further details.

Apply to connect to a sewer now

Apply to connect to a sewer 

We recommend doing it online, but if you’d prefer, you can download and complete a pdf application form.