Fast and reliable Build Over Agreement Service
- Ensure compliance before you dig with our professional support.
- Architects, builders & homeowners trust us.
- Your build, our agreement with zero stress.
- 100% approval rate..
What is a build over agreement?

A build over agreement is a formal approval from your local water authority that allows you to build an extension or structure over or near a sewer. These sewers are usually located beneath private properties and any building work above or close to them could risk damaging the pipes or restricting the future access for maintenance. This is where you will need an agreement from the authorities such as Thames water build over agreement that ensures your proposed construction won’t negatively impact the public drainage system. This approval is usually required if your work falls within 3 meters of public sewers or if you are planning foundations that will go over or near it.
What includes in our build over agreement services:
Planning to build near or over the sewer? Don’t let underground issues stall your dream project. At Paramountbuilt, we make the build over agreement process easy, clear and fully compliant, so you can build with confidence.

Sewer Mapping & Site Assessment
Before any application is made, we conduct an evaluation to identify all the drains related to your project, as well as all the risks associated.

Architectural & Structural Drawings
We ensure that all necessary professionally scaled sketches are completed for the water authority’s consideration and endorsement.

Regulatory & Compliance Advice
We provide a broad and deep understanding to ensure control of building authority and regulations concerning the waterways throughout construction.
How do we deliver your build over agreement?
There is no one who doesn’t want a hassle-free construction process, and at our company, our expert professionals are dedicated to offer you the quality and efficient services that will help you get the approval fast from the utility companies if you are going to build near or above the utility pipes or lines. To keep the stress out of your project it helps you alot. This is why you need it.

Initial Consultation
We talk about your project, look over any documents, and determine if a Build Over Agreement is a prerequisite from the sewer’s proximity and depth.

Site Analysis
We carry out a site visit as a follow-up to the discussion, where our engineers evaluate your property’s existing features, take necessary measurements and construct a complete drainage network.

Drawings & Application
Based on your application, we prepare all the relevant technical drawings together with other necessary documents and forward the application to the concerned water authority.

Approval & Ongoing Support
We provide personalised support and routing assistance after the initial application has been approved, guiding you through the subsequent actions while supporting any further arrangements with building control or your contractors.
When will you need the build over agreement?
A Build Over Agreement is needed to protect and manage construction works that may impact public sewers. It is usually needed in the following six cases:
- When a building is constructed within 3 metres of a public sewer, a certain degree of access must be maintained, which requires permission.
- An agreement cannot be made after work on the foundation plan, which intersects with the sewer line, begins.
- Conversions above and near the drainage routes must secure permission to prevent destruction and guarantee access to the sewage system.
- Newly constructed dwellings or other structures placed within public sewer boundaries must be approved by the water authority in advance.
- Changes to the existing drainage works positioned adjacent to public drainage can affect the public drainage in terms of flow and access.
- Excavating near manholes or sewer chambers without permission risks service disruption and potential enforcement by the local authority.
Unlock your build’s full potential, secure your build over agreement today!
Hire our team that ensures your build complies with sewer regulations and is fully approved.
When won’t you need to submit a build over agreement?
Not every construction project needs a sewer build-over agreement. Sometimes, your building work may be far enough from public sewers, or it may only involve private drainage, thus avoiding the need for formal approval. Here are some cases where an application is typically not needed:
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Your construction is positioned more than 3 metres away from the public sewer and drainage access.
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The sewer is private, only servicing your property and not in conjunction with neighbours.
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If construction is at above-ground level, like loft conversions or non-invasive extensions.
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No impact or alteration was made to the existing sewer or manhole access.
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The sewer runs parallel, not beneath or transverse to the building footprint.
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You have checked with the relevant water authority, and they don't require any consent from them.
How do you get a build over agreement?
While obtaining a Build Over Agreement may seem complex, it is virtually effortless when expert advice is applied. First, your property requires a professional survey to ascertain if the public sewer is impacted by the construction.
After that, all relevant plans, along with the detailed drawings and drainage layouts, are forwarded to your local water authority for their approval. They will evaluate the schemes to make certain that there is no danger to the sewer system and that access for maintenance during the lifetime of the sewer is not obstructed.
Accuracy and compliance in these matters are the most important aspects in which Paramountbuilt specialises. We manage the entire process from start to sign off, which enables you to build with complete confidence without uncertainty from delays or unwanted complications like bureaucratic procedures.

Testimonials
Paramountbuilt 36 Google reviews Elvin Turner2025-05-23 Great consultation! Lielis Andrews2025-05-23 Quick and efficient service. Would use again. Timely visit to property and survey provided within 5 working days. Excellent communication from start to finish. SALINDER PATEL2025-05-23 Great service, did everything they could to ensure i got this within the timeline. Customer service was 5 stars, kept me updated all through the process. Definitely be using them again. Deborah Dunkley2025-05-21 I chose this company after reading their trust pilot reviews. Initially I spoke to Amber who was very knowledgeable on the telephone and was able to speak to me in technical terms which was reassuring. A survey was arranged and carried out for the approaching weekend. Aslan carried out my Survey and he was thorough. I have now instructed them to go ahead and submit my plans for building regs and I know my project is in good hands. Yasemin A2025-05-09 I recently used paramountbuilt for a structural survey on a property I was purchasing, and I couldn’t be happier with their service. From start to finish, the team was professional and thorough. They provided a detailed report that was easy to understand, highlighting all the key findings and offering clear recommendations. Their expertise and attention to detail gave me complete peace of mind during the buying process. Valentina Ljubchinskaja2025-05-08 I applied for a house extension with Paramaunt Build and submitted a planning permission application through the council. At the start, Sophie and Zoe were very nice and helpful. Later, Sumet came on board and did a great job with the painting. I had a few amendments, including some that came after the application had already been submitted, but the team was always accommodating and made the changes as requested — they were truly kind and supportive throughout. Amber helped speed up the process, and I was told that hopefully by 8th May, the council would approve the project. And today, on 8th May, Amber called with the great news — my application has been approved! Right now, we're halfway through the process with the company, and the next steps will be with the building control department. I hope that part goes just as smoothly and efficiently. Once the whole project is completed, I’ll be happy to leave a detailed review. Thank you, Paramaunt Build team!
FAQ’S
There is a distinction between public and private sewers in terms of responsibility and service. Public sewers are the responsibility of the local water authority and serve multiple properties, whereas private sewers serve only one property and are owned and maintained by the owner.
If the conservatory is built within 3 meters of a public sewer, or over one, then you will need a build-over agreement.
In the absence of an agreement, your build could face legal, constructive, or cancellation issues during the selling phase, or during building control inspections, which could lead to inspection issues, delays, or even demolition.
You may apply directly through the Thames Water portal or acquire professional aid, as you must present precise plans alongside drainage arrangements.
Approval usually takes about 3-4 weeks but can differ based on your project’s complexity and the water authority.
With expert planners and compliant documents, it can be made relatively simple, especially for companies like Paramountbuilt, which help streamline the process.