Build over a sewer

If you are building a new property or extension you will need to ensure it does not affect our public sewer mains. Therefore, if your proposals mean building over/near (within 3 metres) a public sewer or lateral drain you will need our approval before doing so.

Within the Southern Water region there are approximately 39,000 kilometres of public sewers, some of which may have been laid within the boundaries of properties. As the sewerage undertaker, we maintain this pipework and need to ensure it is protected for the future to continue serving our region effectively.

Before carrying out any building work over the top of or within three metres of a public sewer you must have our agreement. This is so we can ensure that no damage is caused to our network or restrictions made to the way we use and maintain the sewer going forwards, including our access for maintenance and repair.

For more information please read our Building Over a Public Sewer Guidance Notes, which will take you through the information and steps needed before making an application and the possibility of attaining our approval through your local Building Control or through a Declaration of Works application.

 

Build Over Applications

Below is a guide on what you need to do when making a Declaration of Works or Build over application, including links to make an application via our portal.

Pre-application

Before you make an application it’s important to take account of the following points:

Are you covered by Building Control?

If you are constructing a new building, the first thing is to check if it is subject to the Building Regulations. If it is then you are required to confirm it meets the standards set out in section H4 of the Building Regulations and this can be assessed by a Local Authority Building Control (LABC) department or an independent approved inspector as per your choice.

If compliant with H4 of the Building Regulations then inspectors at LABCs may approve potential build overs on our behalf, however they would need to do so in consultation with ourselves.

If your proposed extension/building is not subject to Building Regulations, or you are not in a protocol area the following guidance will help you to choose and complete the right application for your needs.

Can you apply for a Declaration of Works?

If you have established that your proposal cannot be assessed by Building Control, it is possible you can apply for self-certification through a Declaration of Works.

You will need to meet the requirements for self-certification for us to be able to provide consent to build over/near our assets, so please read through our Declaration of Works Guidance Notes to understand the applicable consent criteria.

If your proposals meet the requirements set out for self-certification, please make a Declaration of Works application via our portal and we will provide consent to build over our assets by letter within 10 working days.

An application fee of £102.00 (incl. 20% VAT) will be required.

If the proposals do not meet the self-certification points, a Build Over application will be required and the following guidance explains this process.

Stage 1 – Make a Build Over Application

Once you have read through the guidance notes and if both Building Control approval and Declaration of Works are not an option for you then you can make a Build Over application by applying via our portal.

You will need to include the following with your application:

  • A site plan (.pdf) (1:100 or larger clearly showing the location of sewers and manholes).
  • A site location plan (.pdf) (1:1250 or larger).
  • Copies of all drawings submitted for building regulations approval.
  • An application fee of £720.00 (incl. 20% VAT).

Once your application has been made, our team will review the information submitted and we will respond within 5 days to confirm the documentation is complete or ask for more information if required.

Stage 2 – CCTV Survey

As part of the process to determine the condition and actual location of the affected sewer, we will need to carry out a CCTV survey. Our CCTV contractor InSewer will be in contact with you to arrange a mutually convenient time to visit your site and carry this out. In some circumstances we will also arrange a site visit by a clerk of works if required.

Where a satisfactory CCTV survey has been provided with your application, or if it was not required, we will arrange a refund for the cost we would have incurred had the CCTV survey proceeded.

Stage 3 – Receive our Response

We will send you our response, setting out any conditions required to be followed for your proposals, within 8 working days after we receive the CCTV survey report for your property. For most properties, this happens within 20 working days from when we received a complete application.

For some sites we may also ask you to complete a Sewer Protection Agreement with us to ensure the protection and future maintenance and access of the sewer. For example, if you were planning to build boundary to boundary of your site. However we will make this clear in our response if this is the case.

Sewer Protection Agreements

Depending on the circumstances of your site, we may ask you in our response to complete a Sewer Protection Agreement (SPA) with us so we can ensure the protection of the public sewer and our future maintenance access.

A SPA is a legal agreement between us - Southern Water - and the property owner to protect the public sewer that is being built over. If the below criteria apply to your plans, then a SPA will be required:

  • Covering 8 metres or more of a public sewer.
  • If the proposal spans from boundary to boundary of your property.
  • Unconventional construction that is not compliant with our Guidance Notes.
  • Impedes access to maintain the public apparatus.
  • If the proposal covers two or more sewers.

 

The Protection Agreement is required because we as a Water Company have a legal obligation to service and maintain public sewers in our area of operation. If the above points apply, then the proposed build-over will make it hard for us to access, repair and maintain the sewer (our statutory duties) in the future to ensure it continues serving our customers effectively. The agreement ensures the rights of access to repair and maintain that public sewer in the future at the landowner’s expense.

A SPA is made against the property, not the property owner, so you must disclose the SPA to any potential new owners in the future should the property be sold.

The legal documentation is prepared by our Legal Department and paid for separately. The SPA costs approximately £250 for domestic/residential properties and £400 for commercial properties and should be completed before commencing works on site.

Once the SPA is complete, we will provide you with a confirmation letter to inform that the works on site can be completed in accordance with the terms of the agreement and conditions outlined.

Diverting an existing public sewer

If the affected sewer requires a diversion (relocation not replacement of existing line) you will be required to apply for a sewer diversion.

For minor sewers (if the pipe size is <225mm and the depth of the sewer is <3.0m) you have the option of requesting a small sewer diversion through a Buildover application. In addition to our standard application requirements, you will need to submit the proposed diverted sewer plan around your proposal (i.e. extension) in line with the Design and Construction Guidance.

The Design and Construction Guidance (DCG) is covered under Appendix C of the Sewer Sector Guidance document, which replaced Sewer for Adoption (SFA). The DCG details the new design and construction standards for adoptable foul and surface water systems.

You will also need to provide consent from neighbouring landowners if the diversionary work takes place on their land. For existing applications, you can upload this to us as additional information.

For critical sewers (if the pipe size >225mm or the depth of the sewer is >3.0m) you can undertake this through a Sewer Diversion.

Transfer of Private Sewers

On 1 October 2011, legislation introduced by the government transferred responsibility for private sewers and lateral drains to Southern Water – providing clear ownership and better long-term maintenance for the sewer network. We’d recommend understanding the changes before making an application.

The changes mean property owners are no longer responsible for certain sewer pipes that connect their homes to public sewers. Our Building Over a Public Sewer Guidance Notes includes a depiction of where the responsibility now sits for different sewers.

 
 
 
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