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1. What is Sewer Adoption?

  • Legislation covering the adoption of sewers, including pumping stations and other ancillaries, is contained within the Water Industry Act 1991. Section 104 covers the adoption of private sewers to be constructed at a future date subject to an agreement with the sewerage undertaker (IWNL).
  • Sewerage assets, offered for adoption, should be designed and constructed in accordance with the standards that are included in the latest edition of Sewers for Adoption. This is published by the Water Research Centre (WRc) and representatives of both the Home Builders Federation and Water UK were involved in its preparation.
  • Once adopted, the sewers are vested in the ownership of IWNL.

2. How to apply for sewers to be adopted under Section 104

  • Complete a Sewer Adoption Application Form and return it to the address on the form, together with the relevant supporting documents. IWNL currently do not charge for this initial application. It is important that the applicant provides us with a fully completed and accurate submission as we reserve the right to charge you for the time spent on assessing your application where we deem the time we spend to be unreasonable
  • In line with Government guidance, we encourage wherever practical, the disposal of surface water via alternative disposal methods other than the public sewerage system. Soakaways or infiltration areas should be used on free draining soils.
  • Where consent to discharge is required from the Environment Agency, British Waterways or Railtrack, the applicant must not agree to any conditions without our prior approval.

3. What happens next?

  • We will acknowledge the application within 14 days of receipt.
  • We will confirm whether the application is complete or not.
  • If the application is complete we will provide a response within 28 days of receipt advising you whether your proposals are acceptable or not.
  • If the application does not meet the criteria, we will advise the applicant of why we have rejected it and what is needed to rectify the situation.
  • Provided the applicant’s proposals are acceptable they will be invited to enter into a Section 104 agreement.

4. How to make an application

To make an application, please download the application form here and send to

5. What if I have a query?

If you have any questions regarding this process please send your enquiry to Alternatively call us on 02920 442 716 from 8am - 5pm, Monday to Friday