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Connecting to a sewer

Important information

We’ve noted that some applications being submitted are missing key information. This will result in your application being delayed.

Please ensure you include the following:

  • Existing and proposed pipe diameter (size)
  • Method of connection (new / existing manhole, Y-junction)
  • Point of connection

View example drawing of sewer connections. You can contact our Help Desk on 0800 009 3921 for further guidance. 

If you’re building a new home or changing your drainage layout, your builder might have told you to apply for permission to connect to a sewer or move a manhole. Here’s what you need to do:

Before you apply

You’ll need to know:

1. What type of sewer connection you need:

  • Foul water sewer: carries wastewater from toilets, baths, showers, sinks, dishwashers, and washing machines.
  • Surface water sewer: carries rainwater from rooftops, roads, driveways, and paved areas.
  • Combined sewer: carries both foul water and surface water.
  • Trade sewer: carries wastewater from industrial premises.
  • Trunk and chemical sewers: usually only used in complex projects.

2. The location of the sewer that you’d like to connect to.

There are several ways to work this out:

  • 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, 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.
  • Sewer records can be viewed at local council offices.
  • You can buy sewer and utility maps from several property search providers, including Thames Water Property Searches.
  • A drainage specialist can give you advice on how to locate a sewer.

3. Who owns the sewer:

You'll only need our permission if you're connecting directly to a public sewer.

If you're connecting to a private drain that discharges to a public sewer, known as an indirect connection, you’ll need permission from the drain owner as well as us.

4. Where you want to connect to the sewer or where you’ll be relocating the manhole.

Planning permission

If your project is covered by a planning application, this must be granted before we can approve a sewer connection application. Please have a copy of your planning permission to hand when applying.

Learn more about how to understand your requirements before applying for a sewer connection.

Applying to connect

Here’s what you need to apply:

  • Detailed drainage plan in scale 1:100 – 1:500, showing your entire site. This should include:
  • All buildings & roadways
  • Location and direction of flow of all private sewers/drainage
  • The proposed connection point to the public sewer
  • See an example drawing 
  • Site location plan in scale 1:500 – 1:1250, showing your site boundary within the surrounding area.
  • Copy of planning permission if relevant to your project.

You can prepare the plans yourself or ask a drainage consultant to do this.

Application costs

  • Direct connection £270
  • Indirect connection £215
  • Manhole relocation £270

See our connection terms and conditions for more details.

Download sewer application form

You don't need to print the form, you can type your answers into the boxes provided. Once completed, please email your application form to developer.services@thameswater.co.uk.

Learn more about the next steps once you've applied to connect to a sewer.

Technical review

Our team will review your application to make sure it meets our requirements and national specifications.

  • This takes up to 21 days and we’ll then be in touch with the results
  • Once we have approved your application, we will issue you a 'Consent to connect'
  • You can then appoint a contractor to do the connection works

If you’re connecting to a private drain that discharges to a public sewer, this is the end of the process.

If you’re connecting directly to a public sewer or relocating a manhole, then you’ll need to get an inspection from us.

How to get an inspection

We’ll need to inspect the work if you’re connecting directly to a public sewer or relocating a manhole. There are a few steps to remember:

  • The work needs to be done exactly as described in the ‘Consent to connect’
  • If the work isn’t finished when we come out to inspect it, we’ll charge you to come back another time
  • Make sure you leave the trench open so we can fully inspect the work

Call us on 0800 009 3921 Monday to Friday, 8am – 5pm to arrange an inspection. We need at least 10 days’ notice.

Once you’ve passed the inspection, we’ll issue a certificate. This confirms that your work has been completed to the required standard.