Building over a sewer

Are you considering extending, renovating, or building a new property? We’re sure you’re excited and possibly a little daunted too. To help your project be a success, we’ll explain why it's important to consider any nearby sewers at this stage.

Why is considering nearby sewers important?

Building an extension, a new property, or renovating can be an exciting time, but it can impact the public sewer network serving you and your neighbours. Some extra planning may be needed if you're going to be building over or near a sewer.

If you’re planning to build within three metres of a public sewer, you’ll need to submit a build over application. We're here to help and guide you through an application.

Here are a few reasons why it's important to get our permission:

It helps to prevent damage to the sewer

If not considered, building near a sewer could cause them to collapse under the weight of the new structure. This could damage your property, interrupt drainage for other properties, and increase the likelihood of flooding.

Submitting a build over application allows us to check the necessary precautions are in place and that the sewer is in good structural condition.

We need constant access to our network

We’ll also check that your plans allow for 24-hour access to all public sewers and manholes. We need this to be able to carry out routine inspections, maintenance, and repairs. These are essential to help us protect your home and our pipes.

You’ll need the correct paperwork

A building control surveyor will expect to see our permission before giving you a completion certificate or ‘sign off’ your work.

If you sell your property in the future, the buyer’s solicitor may ask for a copy of the Build Over Agreement showing our permission. Without this, selling your property could become more complicated.

Log in to the GetConnected portal

You can apply for permission to build over or near a sewer, including extending near an existing sewer, through our GetConnected portal.

When won't you need to submit a build over application?

If you're constructing a new extension
Building over a sewer

If you're building or undertaking changes to a non-residential building over or near a public sewer. In this case, you may need to request a sewer diversion. If you're unsure, please contact us.

Building proposals we won't accept:

Over or near public infrastructure

Building over or near public water mains, pumped or rising mains, vacuum mains and strategic or ‘trunk’ sewers.

Over or near existing sewers

Building over or near existing sewers on new development sites or re-development sites. Instead, you can look to divert the sewer, or to save cost, adjust your plans so that your building is at least three metres from the sewer.

Over internal an manhole or change in pipe direction

Where there would be an internal manhole or change in pipe direction (i.e. Y-connection or a junction of a public sewer) within the proposed building. These are not allowed due to potential odour and flooding issues. You’ll need to relocate these outside the property, where we have full access, to get approval.

If there are easements or restrictive covenants

If there are easements or restrictive covenants on the pipework by your proposed works, we won’t allow you to build near or over the pipework.

Impact access to existing sewers

The pad, raft and cantilever foundation types over the public sewer are not permitted as they can impact our future access to repair the adjacent public sewer. This can significantly increase the risk of damage to the structure during repair works. We also don't permit reinforced concrete floor slabs over public sewers for the same reason.

If you have a Boundary-to-Boundary infill structure

Where there are already structures on both sides of the boundary, that will restrict future access to the public sewer.

Making an application for a Build Over Self-Declaration

It’s likely you can progress with a self-certified build over approval known as a Build Over Self-Declaration if:

As part of the application process for building over a sewer route, we ask you to complete a list of questions to determine if you meet the criteria. The below guide shows the application process step by step. Before applying, you should make sure that you've got:

Copies of all drawings submitted for building regulations approval.

The step-by-step process

Apply online

Fill in our online form, submit your required documents and pay a fee for the self-declaration using our GetConnected portal. We’ll review your application within five days and let you know if we have everything we need to progress.

We'll send you a conditional approval

We'll review your application and send you a conditional approval letter within the next two weeks. You'll need to share this confirmation with your builder. If you're relocating a manhole chamber or undertaking minor pipe repairs, you'll need to pay an inspection fee of £84. Your letter will state if this is needed.