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Sewer diversion

If you need to request a diversion or change to one of our sewer mains, you'll need to apply for a sewer main diversion online.

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Sewer main diversion application process

Where there is a sewer main affecting your planned development, you may need to divert the main. We can assess your proposal and comment on the design options through a sewer main diversion.

You can either carry out a Southern Water or developer-led sewer main diversion. The legal and financial arrangements will differ depending upon who is carrying out the work. 

As a developer-led sewer main diversion, you can carry out the works where the following applies:

  • It's a non-critical diversion

    The apparatus to be diverted is categorised as non-critical

  • It's within your boundary

    The route of the sewer diversion remains entirely within the boundary of your land

You'll want to opt for a Southern Water sewer main diversion if:

  • It passes through someone else's land

    The route of the diverted sewer passes through third-party land

  • It's a critical sewer

    The sewer being diverted is a critical sewer (this includes all rising mains), or there are specific operational requirements

  • The sewer to be diverted is a bonded asbestos cement pipe

    This includes pipes described as asbestos cement (AC) and fibre-reinforced cement (FRC)

Developer-led diversion Southern Water sewer main diversion
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Developer-led diversion

Before you apply, please read our Developer Sewer Main Diversion Guidance Notes. These will take you through the process, including:

  • A site plan (.pdf) at 1:2500: development site edged in green and clearly detailing any roads, adjacent buildings and the private pipe run to our network
  • A site location plan (.pdf) at 1:1250 (or larger)
  • A drainage layout plan (.pdf) at 1:100 (or larger), showing the location of sewers and manholes on site and up to the connection point
  • Manhole construction and Longitudinal section details (.pdf)
  • Third-party landowner information (if applicable)
  • A copy of your planning consent
  • An application fee of £451.13 (inc. 20% VAT) will be required.
1

Apply for a sewer main diversion online

Fill in our online form through GetConnected and pay your application fee. We’ll review your application within five days and confirm whether the documentation is complete or if we need more information.

2

Application approval

We’ll review your application and send our decision or request further information within 28 days. When the proposal meets our standards, we will provide you with the compliance letter. This will include our estimate of the cost of adoption and any required fees.

3

Accept and pay

Once you're ready to accept, you should make payment for the fees set out in your compliance letter.

4

Section 185 agreement

We’ll arrange for a legal agreement to be created and signed before the work begins.

Our team will also find a suitable time to carry out a commissioning inspection.

5

Complete the diversion works and request inspections

Once construction has started, contact us and request an inspection. When you've completed the sewer construction, you'll also need to request a sewer adoption maintenance inspection.

This inspection will confirm that the works are suitable to be placed on ‘12 months maintenance’ and we’ll issue a provisional certificate.

6

Final inspection and completion certificate

Three months before the end of your maintenance period, you can request a final inspection of the adaptable system. Once we're satisfied all remedial work is completed, we’ll issue the final certificate.

The legal vesting of the sewers will happen soon after.

Southern Water sewer main diversion

The following step-by-step guide is for when you've decided that we'll carry out the work. You can apply for this using our GetConnected portal.

Before applying, please read our Southern Water Sewer Main Diversion Guidance Notes. This will take you through the process, including:

  • A site plan (.pdf) at 1:2500: development site edged in green and clearly detailing any roads, adjacent buildings and the private pipe run to our network
  • A plan (.pdf) highlighting the length of the main you would like to divert and the location you would like it moved to if you have a preference
  • Your proposed drawing in a .dwg format. This will need to be compatible with AutoCAD
  • A soil analysis report
  • A copy of the existing wayleave/easement agreement (if available)
  • An application fee of £2683.60 (inc. 20% VAT) will be required.
1

Apply for a sewer main diversion online

Fill in our online form and pay your application and design fees. We’ll review your application within five days and confirm that the documentation is complete or if we need further information.

2

We'll send a budget estimate offer

Within 12 weeks, we'll assess the initial feasibility, create an outline design and send you a preliminary budget estimate offer for the work.

If the design is straightforward, a budget estimate may not be required. We'll let you know if this is the case and provide you with a detailed design offer in the first instance.

3

Accept the offer and pay

Once you are ready to accept the offer and pay the fee to progress to detailed design, you'll need to do the following:

  • Complete and return the remittance form.
  • Make payment for the detailed design fee.

Once you have completed this and paid, we will assign a Project Manager as your point of contact for the next steps in the process.

4

We'll complete your design and schedule works

Once we've agreed on the budget estimate design and you have paid the detailed design fee, we'll pass the site onto our Project Delivery team. Your assigned Project Manager will confirm the final delivery route before scheduling any construction works.

5

We'll complete the work

Our Project Delivery team will confirm a start date, schedule and completion date for the onsite work with you.

After construction is complete, we’ll update our maps with the diverted route.

Need more support?

We're here to help if you have any other questions. Please fill out this form in as much detail as possible to help us answer your query.

Repaired a leak

This can be found in the top right corner of your bill and is 8 or 10 digits long.

This is the reference on the back of the leaflet that one of our members of staff left with you