The planning and construction of a new property development can be derailed if proper attention isn’t paid to the sewers. If new drainage systems aren’t legally or safely integrated into the public network, developers will likely face significant structural, legal, and financial consequences. Because of this, it is essential to get approval before any groundwork begins.

Navigating this approval process smoothly requires a solid understanding of sewer adoption. In this guide, we’re going to break down everything you need to know about securing a Section 104 agreement, from the initial paperwork to final hand-off.

What is a Section 104 agreement?

Also known as an S104, a Section 104 Sewer Adoption Agreement is a legally binding agreement between a property developer and its local water and sewerage company (WSC), also still sometimes referred to as the local water authority (LWA). 

This agreement allows the developer to construct a new private sewer to be maintained by the water and sewerage company once work has been completed. It falls under section 104 of the Water Industry Act 1991, which is a government legislation that establishes the duties and powers of water and sewerage companies across England and Wales.

How Section 104 agreements work

While the 1991 Act provides the legal foundation for the S104 application, the process itself is governed by the Code for Adoption. This is a regulatory framework created by Ofwat (the Water Services Regulation Authority), which governs how the developer and water company must work together.  This was introduced to unify the sector, preventing the delays and frustration that came with each water authority working to its own unique set of standards.

The Code for Adoption framework shapes how your S104 agreement operates for the better:

• Enforced timelines: Under the Code, water and sewerage companies must abide by strict Service Level Agreements, known as SLAs. They are legally required to review your submissions and conduct site inspections within set timeframes. This protects developers from project delays that could be costly.
• Standardised contracts: Legal sign-offs are unified under the Code, making them more efficient and cost-effective. Before, each water company had different contracts, which meant those developing across multiple regions had to spend a great deal of time signing multiple contracts for the same purpose.
• The adoption of SuDS: Water companies are now equipped to adopt nature-based SuDS (Sustainable Drainage Systems). As long as the ponds, swales, or wetlands are designed to the standards laid out in the DCG, they can be written into your Section 104 contract and therefore maintained by the local water and sewerage company (WSC).

What is required for a Section 104 application

Your application must include all of the necessary paperwork, which in turn must comply with current frameworks. 

The paperwork checklist

The following documents are needed for an S104 application submission:

• A developer programme, including details of construction phasing, surface water strategy, and SuDS.
• A location plan. There are specific requirements for these, including strict criteria about scale and size, as well as elements such as surrounding road names, precise development boundaries, and industry-standard colour-coding for foul sewers, surface water sewers, and sewer easements.
• Longitudinal sections of the sewer and rising mains.
• Copies of hydraulic design calculations.
• Manhole schedules.
• Typical construction details.
• An adoptable drainage layout.

You may find slight differences in Section 104 application requirements depending on where your site is located, so it’s worth checking with the specific sewerage company in question.

The design standard

All drawings in your Section 104 application must be fully compliant with the Design and Construction Guide (DCG) published by Water UK. This is a mandatory technical framework enforced by the Code for Adoption. 

It’s important to note that the DCG completely replaced the old ‘Sewers for Adoption’ guidelines back in 2020. If your drawings and other relevant materials haven’t been updated to comply with the new specifications, your application will not be approved.

Why you should hire a drainage contractor for the application process

Your best chance at getting a Section 104 Sewer Adoption Agreement approved is by working with a drainage contractor, such as Premier Drainage Solutions. Our team take care of the complex application process as part of our service. We have years of experience in producing detailed, compliant plans, ensuring a smooth and successful application process to save you time and effort. 

You do not get your application costs back if the submission fails, which is why it is essential that it’s at the right standard to be accepted the first time.

The Section 104 project lifecycle

The start-to-finish process of an S104 project can be split into four phases: the paperwork phase, the construction phase, the inspection phase, and the maintenance phase. While the submission of your application happens in the first phase, because it is a legally binding contract, there are obligations that must be fulfilled throughout the rest of the project.

Each local water company will have a slightly different process for the S104 application, so it is crucial to check your specific WSC website for their latest timelines to avoid any delays to your project.

The S104 paperwork phase:

1. Capacity and connection check: A pre-planning consultation is held with the WSC to help them check if the existing network has enough capacity to serve your proposed development.
2. Submission and signing: The paperwork for the application is gathered, the application is submitted, manhole schedules are sent to the WSC, and, if all is approved, all parties sign the S104 contract.
3. Construction agreements and fees: A programme of works and an inspection timetable are agreed upon with the WSC. All fees, including vetting and legal, must be paid at this point.

The S104 construction phase:

4. On-site construction: The approved drainage contractor, such as the team from Premier Drainage Solutions, begins the physical works.
5. Routine inspections: The WSC carries out construction inspections on site, including checking the construction quality, manhole build, and air and water testing if necessary.

The S104 inspection phase: 

6. Pre-maintenance inspection: Before the project’s mandatory maintenance period begins, the WSC inspects the manholes and asks for a full, professional CCTV survey as part of the pre-maintenance inspection. Any identified problems during this inspection must be rectified before the WSC can issue a provisional certificate of completion. Sometimes, the water company will want to conduct the CCTV surveys themselves, but often you will be able to arrange this with an independent drainage company.

The S104 maintenance phase:

7. Maintenance and final inspection: The developer is responsible for the maintenance costs and upkeep of the sewer system during this 12-month period. At the end of the maintenance period, the WSC carries out a final inspection. If any problems are found, such as defects or ground settlement issues, remedial work must be completed. 
8. Vesting and adoption: Once deemed completed to a satisfactory standard, your WSC formally signs off on the project. All legal easements and land rights are finalised, and the developer is released from defect liability. They then issue a vesting certificate to confirm the adoption of the new sewers. From this point, the WSC takes responsibility for maintaining the sewers.

Please note that the Code for Adoption recommends that developers do not start constructing any new sewers intended for adoption until all parties involved have formally signed the legal Section 104 agreement. Starting construction before then is done entirely at your own financial risk, as the WSC may later demand design changes at best, and entire system replacements at worst.

How much do S104 applications cost?

Typically, costs for a Section 104 Sewer Adoption Application include an amount to cover technical and vetting services, legal fees, and a security deposit. 

We are qualified to perform the necessary CCTV survey as part of the pre-maintenance period inspection. The cost will vary depending on the scale of the property, but our condition surveys start from £365.

Currently, these are the costs with Thames Water, Anglian Water, and Southern Water, the local water companies we work with across East Anglia and the southeast:

Thames Water:

Please find full information on the Thames Water website. These prices are accurate as of May 2026.

• S104 application cost for a direct connection: £390
• S104 application cost for an indirect connection: £290
• S104 application cost for a manhole relocation: £360
• Application fee: £1,725
• Project management and inspection fee: 1.4% of the estimated construction cost
• Legal fee (adoption agreement): £1,050 
• Easement fee (to formalise access rights): £905
• Security deposit: either £5,000 or 10% of the construction cost estimate

Anglian Water

Please find full information in Anglian Water’s 2026/2027 Development Charging Arrangements document. These prices are accurate as of May 2026.

Application fees for Section 104 vary by development size:

• Foul sewer only:
  • First 100 plots or fewer: £814
  • Per 100 plots thereafter (or part thereof): +£366
• Surface water only:
  • First 100 plots or fewer: £936
  • Per 100 plots thereafter (or part thereof): +£427
• Additional S104 add-on applications
  • Pumping station (per item): £488
  • SuDS (per application): +£651
• If you plan to build both a foul sewer and surface water sewer, they must be applied for separately, and the application costs will be stacked.

Other charges:

• Supervision (site inspection) – 2% of estimated construction cost (minimum charge £1,058)
• Surety: 10% of estimated construction cost (minimum charge £5,000)
• Legal agreement: £628 (complex amendments charged at £151 per hour)
• Fourth and further vetting task fees will apply (three vetting tasks are included in the standard fee)

Southern Water:

Please find full information in Southern Water’s New Connection Charging Arrangements 2026/2027 document. These prices are accurate as of May 2026.

• S104 application fee: £668
• Inspection fee: 2.5% of the construction value
• Legal fee: £518
• Bond: 10% of the construction value

Hire Premier Drainage Solutions to help you navigate the Section 104 sewer adoption application process

With decades of experience working in the sewer industry, we are well equipped to assist you with or file directly for your Section 104 Sewage Adoption Agreement application. We produce fully compliant plans and documents, ensuring a smooth and stress-free application process. 

To enquire about our sewer connection services, including our Section 104 applications, visit our contact page for our phone number, WhatsApp number, email address, and call request form.

Information in this article is correct as of May 2026 and sourced from the local water authorities named below. For further location-specific Section 104 application details within the southeast, visit Thames Water, Anglian Water and Southern Water.