Connecting to a sewer

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:

Direct connections

You'll only need our permission if you're connecting directly to a public sewer. In most cases public sewers are shared with two or more neighbouring properties.

Indirect connections

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.

Private drains are usually not shared with neighbouring properties. They only take the drainage from one single property.

Manhole relocations

You’ll only need our permission if you’re relocating one of our public manholes.

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

Once you've established where you want to connect, you can confirm the type of connection you’re making. This will be a connection into:

• A new manhole
• An existing manhole
• The sewer pipe using pre-formed Y-junction
• Or a manhole relocation

Applying to connect

Here’s what you need to apply:

• Drainage layout plan clearly showing:
  • Your entire site with all buildings and roadways
• Location of existing and proposed sewer features including:
  • Point of connection
  • Methods of connection (new/existing manhole, Y-junction)
  • Pipe sizes
  • Direction of flow
  • Gradients
  • Invert levels

Use of varying colours and/or symbology should be used to clearly differentiate between existing and proposed features. This must include existing private drainage (if any) up to the existing connection point(s) with the public sewer(s), as well as public sewers in the vicinity of the site.

• Site location plan in scale 1:500 – 1:1250, showing your site boundary within the surrounding area.

For manhole relocations/modifications, we'll require also a cross-sectional plan. This should show the existing and proposed manhole arrangement.

See an example drawing.

• 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 £370
• Indirect connection £310
• Manhole relocation £370

See our connection terms and conditions for more details.

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

For more information and guidance on how to apply, please contact us on 0800 009 3921 Monday to Friday 8am - 5pm.

How to get an inspection

We’ll need to inspect the work if you’re connecting directly to a public sewer or relocating/altering one of our manhole chambers.

Call us on 0800 009 3921 Monday to Friday, 8am to 5pm to arrange an inspection. Please try to give as much notice as possible to accommodate your preferred inspection date.

There are a few points to remember:

• The work needs to be done exactly as described in the ‘Consent to connect’ and as per our agreed specification
• You should be ready with all work completed to be inspected on the date of inspection
• Make sure you leave the connection point open so we can fully inspect the work 

If you fail to comply with any of the steps above at the time of inspection, we will charge you to come back another time. The revisit fee is £245 plus VAT, per visit.

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