Building and Developing

man digging
New site developments
If you're building multiple domestic or commercial properties on a site that will have a new road/access you'll probably need a new water main. You can choose either STW or a WIRS accredited Self Lay Provider (SLP) to lay the new main and/or service connections. Proposed sewers into the site can be offered to us for adoption so we become responsible for them.

Sewer Adoption - New Site

Codes for adoption

From April 2020 Ofwat have introduced a standard practice across the Water Industry in England that all companies will follow regarding the adoption of newly constructed sewers. 

In October 2019, Ofwat approved the sewerage sector guidance documentation (SSG) to meet the requirements of the Code. From 1 April 2020 this guidance will come into force standardising process and procedure across the country.  As part of the SSG, ‘Sewers for Adoption’ has been replaced by the mandatory ‘Design & Construction Guidance’ (DCG) which gives provision for Sewerage Undertakers to adopt SUDs facilities.

Below is a helpful guide that sets out what you’ll need to do to offer new assets for adoption under the codes for adoption.

Step One - Pre-Planning Enquiry

This stage is designed to confirm the allowable rates of discharge to the point(s) on the existing network where a connection to a public sewer is required. Our team will also advise on any known capacity issues within the area and any diversions or requisitions that may be required.

You can apply for a developer enquiry using our developer enquiry application form which should be returned to or the postal address on the application.

Our Network Solutions team will look after your developer enquiry and if you have any queries, they can be contacted at

You can also view an area map (PDF) for further details.

Following receipt of your developer enquiry response you may wish to talk to our Sewer Adoption Design Team about your sites strategy prior to completing a S104 submission. You can do this by simply completing our Pre-Design Strategic Discussion request application form

This stage helps with early engagement to capture the design of a site and enable the proposals for maintaining a sewerage system for its lifetime to be considered by the Sewerage Company. The earlier the discussions the better, being useful at any point before the S104 application is requested by the developer or recommended as part of the pre-planning enquiry.  It also allows the developer to confirm the future owner and maintainer of the sewerage system at the outset to use as part of their planning application.

Our Developer Services team can be contacted on 0800 707 6600 for further information. 

Step Two - Design of a new sewerage system

This stage is designed to confirm with the developer that the system conforms to the Codes of Adoption to enable a S104 Agreement to be entered into. It will confirm the technical acceptance of the design. It also allows the developer to determine the cost of the works at the outset of the development.

Sewers should be designed as per the Design & Construction Guidance (DCG) which is part of the Sewerage Sector Guidance (SSG)

To make an application for the adoption of a new sewerage system you will need to complete a S104 application. For help with your application please contact our Developer Services team on or 0800 707 6600.

If you are offering a pumping station for adoption, you will need to refer to the Severn Trent addendum on pumping stations.

Step Three - Adoption Agreements

When you have your technical approval in place for your S104, you will need to enter into a S104 agreement so we can formally adopt the sewers. As part of the SSG there is a Model Sewer Adoption Agreement available online. You can either prepare your own agreement using this template or ask us to produce one by providing the required documentation detailed in your technical compliance letter. 

No alterations to the Model Sewer Adoption Agreement will usually be permitted.

We appreciate that construction work may need to begin before the S104 agreement has been signed by all parties. So not to delay the start of your construction work, you can view and download an Early Start Request form (PDF) once you have received conditonal or technical acceptance and made payment of the S104 fees. The early start request form can be submitted to we will then be in touch to arrange a pre-start meeting on site.

Step Four - Construction of sewerage system

Before construction work begins on new sewers proposed for adoption, a pre-start meeting must be completed. A Pre-Start Form (PDF) can be downloaded and submitted via

Once we’ve received this one of our Waste Construction Project Managers (WCPMs) will get in touch with to arrange a pre-start meeting. During construction we’ll carry out inspections to ensure that the sewers are built as per the agreement. Our WCPMs will visit the site by appointment and also on a pro-active basis to ensure compliance with the agreement.

When a sites sewers are constructed and you reach 51% property occupancy, it becomes eligible to progress onto maintenance.

Step Five - Maintenance

When your sewers are ready to begin a maintenance period, please let us know by filling out a Pre-Maintenance Inspection form (PDF) and emailing it to us at before we can complete a maintenance inspection you’ll need to confirm/provide the following:

  • The signed agreement is in place
  • The telemetry installed on any pumping stations is offered for adoption
  • A full suite of As-Built drawings (in accordance with Agreement or variation drawings) including any manufacturers details for each element to be progressed
  • CCTV survey
  • Details of any site hazards found during construction
  • Confirm Health & Safety details for Inspection with any Traffic Management to undertake inspection activities safely

One of our WCPMs will then arrange to carry out a maintenance inspection to confirm that the works are suitable to enter a 12 month maintenance period. Subsequently, we’ll issue the provisional certificate.

Step Six - Vesting


When there are 3 months remaining on your maintenance period we’ll contact you to arrange a final inspection. Alternatively you can contact our team or your WCPM.

You will need to confirm that any necessary remedials have been completed and let us know of any operational issues than have occurred. A final inspection can then be arranged and completed. When any outstanding remedials or legal issues are resolved we’ll happily issue the vesting certificate. 

You can also apply for this inspection using the Final Adoption Inspection Request form (PDF) if you’re not ready when we contact you. 

Step Seven - Variations

This stage is designed to confirm changes to the proposed design of a system for adoption once technical acceptance has been issued. You’ll need to contact us regarding any variation to your design so we can assess if they are minor variations that can be accounted for on the as-built drawings or if a formal reassessment is required. Please contact for further details.

Local Practices

As part of the overarching changes to the Water Industry Act 1991, that introduces statutory Codes for adoption agreements, water companies are requested to publish their proposals to implement local practices, i.e. where there is deviation from the standard practice.

With the advent of the Design & Construction Guidance (DCG) we’ve amended our existing pumping station addendum to align with this latest standard. The pumping station specification in the DCG is primarily the same as those detailed in the Sewers for Adoption 7th Edition.  Therefore, our addendum has minor change only that primarily relates to wording.  There is no significant change in terms of design specification although we would draw your attention to the more detailed Pump Lifting Arrangements section.

Our consultation period for the pumping station addendum has now ended. We received no feedback on our proposed standards and have therefore
made no changes to the original proposed document. We have however reformatted the document and more clearly showed the document history.  

We are proposing a local practise on easements to come into place on 21 September 2021. Should you have any feedback or questions you wish us to consider as part of our consultation, please send an email to by 1 September 2021.

Transitional Arrangements

Ofwat has set 1st April 2020 as the date when the Sewerage Sector Guidance (SSG) and related documents come into force. It’s acknowledged that a hard-cutover date is not viable and thus transitional arrangements have been proposed. These transitional arrangements can be viewed on the Water UK website  and are aimed at enabling our developer customers and companies to work together to more easily transition from the old way to the new way of doing things.


Whilst we aim to support you and deliver for you in a timely manner across the entire process we may occasionally fall short. If this is the case we shall email you regarding the nature and cause of the failure and set out our proposals to resolve. We’ll do this within one working day of the failure occurrence.

Should you believe our proposals to resolve are unacceptable you can request escalation to our compliance manager at who will respond within 5 working days of receipt.