Connecting to a trunk or chemical sewer

Connecting directly to a trunk or chemical sewer can be complex and dangerous. Where a connection to a trunk or chemical sewer is necessary and you are unable to find an alternative sewer or method of discharge, we’ll carry out the work ourselves under Section 107 of the Water Industry Act 1991 (‘the Act’).

Trunk sewers

Trunk sewers collect the flow of sewage from local sewers, rather than individual properties or developments.

Connections to trunk sewers should only be considered if no alternative points of connection to local sewers are available. We don’t allow connections to trunk sewers in greater London – instead, you will need to choose an alternative point of connection to a non-trunk sewer or requisition a new connection and associated pipe laying from us. If you apply for a requisition we’ll select a suitable connection point, which may not be your preferred connection point.

Chemical sewers

Chemical sewers collect flows with high contaminant levels from industry, which can be highly toxic or caustic. Connections to trunk sewers should only be considered if no alternative points of connection to non-chemical sewers are available.

Connection to a trunk or chemical sewer may cause delays and additional costs:

  • Man-entry surveys may be required to determine the line, level and condition of the sewer. These may need to be carried out at night, when flow in the sewer is less. Heavy rainfall or emergency work could also delay this.
  • Permission from the highway authority may be required if we need to carry out work in a road. It can take several months to get permission.
  • Method of connection can add time and cost.
  • Site restrictions may affect us making the connection at the required time.

Here's what happens:

Our technical team will review your application and call you within 14 calendar days to confirm whether we require more information or whether we will process your application under Section 107 of the Act.

Once we have all the information we need we’ll contact you to arrange a site condition survey to assess the feasibility and suitability of your proposal and send you a report. The consent to carry out the connection will then be issued.

Apply now

Connections to trunk or chemical sewers are charged differently to connections to local sewers. Please see Section 7 of our Charging arrangements for new connection services for more details.

Once we’ve consented to carrying out the connection we’ll call you to discuss the costs of carrying out the connection. You’ll then receive the connection quote and schedule or works via letter.

Make payment

You can either pay the full amount on the quote in advance, preferably online with your credit or debit card, or pay in arrears if you provide security equal to the expected charges (including an inflation allowance). You’ll need to quote the reference number starting ‘DS’ from your quote. If you’ve any queries about your quote, please call us on 0800 009 3921.

Pay now

When we’ve received payment or have been provided with a security, we’ll apply for the appropriate traffic management permits and carry out the connection works.

Once we’ve made the connection we’ll carry out another survey to ensure there are no issues. You’ll then receive a completion certificate. If any issues are found, we will discuss the next steps required with you.