Building with Confidence: Navigating Build Over or Near Agreements with the Water Company in the UK

Embarking on a construction project, particularly an extension or new build, often involves careful consideration of existing infrastructure. For any development near or over a public sewer, obtaining a Build Over or Near Agreement with the Water Company is not just a formality; it’s a critical legal and structural requirement in the UK. Ignoring this crucial step can lead to significant delays, costly remedial work, or even the forced demolition of non-compliant structures.

This comprehensive guide will explain what a Build Over or Near Agreement with the Water Company entails. We’ll delve into why this consent is indispensable, when you need it, outline the precise application process, and highlight the severe consequences of non-compliance. Ultimately, understanding these agreements ensures your development is safe, compliant, and future-proof.

What is a Build Over or Near Agreement with the Water Company?

A Build Over or Near Agreement is formal consent obtained from the local sewerage undertaker (your water company, e.g., Thames Water, Severn Trent, United Utilities). This agreement is required when:

You plan to build any new structure directly over an existing public sewer.
You plan to build any new structure within a certain proximity (typically 3 metres, though this can extend depending on the depth and size of the sewer) of a public sewer.

This agreement is separate from, and in addition to, both planning permission and Building Regulations approval.

Why is This Agreement Absolutely Necessary?

Ignoring or overlooking the need for this agreement carries significant risks:

Protecting Public Sewers: The primary purpose is to safeguard the integrity of the public sewerage system. Building over or too close to a sewer can cause damage, obstruct maintenance access, or even lead to collapse.
Legal Obligation: This requirement stems from the Water Industry Act 1991 and is incorporated into Building Regulations. It is a legal obligation for developers.
Future Property Sales: Without a valid agreement, your property may be deemed unmortgageable. This can create a significant problem when trying to sell, as conveyancers will flag the absence of this crucial document.
Ensuring Safety: Construction over a sewer without proper structural design can lead to ground movement, structural failure of the building, and potential risks from escaping gases or sewage.
Avoiding Enforcement Action: The water company has statutory powers to stop work, or even demand the alteration or demolition of any non-compliant structure that damages or obstructs a public sewer.

When Do You Need a Build Over or Near Agreement with the Water Company?

You generally need this agreement for:

Extensions: Adding an extension to an existing property.
New Builds: Constructing a completely new house or commercial building.
Outbuildings: Even sheds, garages, or garden rooms if they are close to or over a public sewer.
Foundations: Large or deep foundations, even if they don’t involve a full building, might require consent if they’re near a public sewer.

Crucial First Step: Identify the location of all public sewers on or near your property. You can often do this via online maps provided by your water company, or by ordering a “build over search” (sometimes called a “sewerage map search”).

The Process of Obtaining an Agreement: A Step-by-Step Guide

Securing a Build Over or Near Agreement with the Water Company is a structured process demanding detailed information:

I. Identification & Preliminary Design

Locate Sewers: Use your water company’s online mapping tools or a sewer search service to identify all public sewers on or near your site.
Early Design Considerations: If a sewer is present, your architect or engineer should, ideally, design your foundations to span the sewer or ensure adequate clearance. Avoiding building directly over a sewer is always preferred. Diversion of the sewer is possible, but usually very costly and requires the water company’s approval.
Maintain Access: Ensure that manholes or inspection chambers remain accessible for future maintenance by the water company.

II. Application Submission

Identify Your Water Company: Submit your application to the correct sewerage undertaker for your region (e.g., Anglian Water, Dŵr Cymru Welsh Water, Northern Ireland Water, Scottish Water, Southern Water, South West Water, Thames Water, United Utilities, Wessex Water, Yorkshire Water).
Required Documents: The application typically demands detailed plans and supporting information, including:
- Site Location Plan: Clearly showing property boundaries and sewer location.
- Detailed Proposed Plans: Architectural drawings, including foundation plans showing how they interact with the sewer.
- Structural Calculations: Provided by a structural engineer, demonstrating how the proposed building will bridge or protect the sewer.
- Drainage Plans: Showing all new and existing drainage.
- Ground Investigation Reports: Sometimes required, especially for larger or more complex projects.
Fees: Be prepared to pay a non-refundable application fee.

III. Assessment & Approval

Water Company Review: The water company’s engineers will review your application. They will assess the structural integrity of your proposed design. They will also consider potential impacts on access for future maintenance.
Requests for Amendments: They may request amendments to your plans or additional information to ensure the sewer’s protection.
Formal Consent: Upon satisfactory review, a formal written consent (the “Build Over or Near Agreement”) will be issued.

Consequences of Non-Compliance

Failing to obtain or adhere to a Build Over or Near Agreement with the Water Company can lead to severe repercussions:

Work Halted: The water company has the power to stop all construction work immediately if they discover non-compliance.
Demolition Orders: You could be ordered to alter or even demolish parts of your building that are non-compliant or obstructing a public sewer. This leads to immense financial loss.
Building Control Issues: You may struggle to obtain a Building Control Completion Certificate. This is a vital document for property sales.
Property Unsallable: Without the agreement, your property could be unmortgageable. This makes it extremely difficult to sell in the future.
Liability for Damages: You become fully liable for any damage caused to the public sewer during or after construction. This includes the cost of repairs and any associated environmental cleanup.

Working with Professionals

To navigate this complex process smoothly, it’s highly recommended to work with:

Architects & Structural Engineers: They can design foundations and structures that comply with water company requirements.
Specialised Planning Consultants: They can manage the application process on your behalf.
Engage Early: Consider pre-application advice with your water company’s build over team. This can identify issues before full submission.

Conclusion: Plan with Precision for Seamless Development

Obtaining a Build Over or Near Agreement with the Water Company is an indispensable step for any development project in the UK involving public sewers. It ensures the longevity of critical infrastructure, safeguards your investment, and protects you from severe legal and financial consequences. By understanding the requirements, preparing thorough documentation, and working with experienced professionals, you can confidently build near or over sewers, ensuring your development is compliant, safe, and future-proof.

Ready to ensure your development project meets all necessary water company regulations?