Build-over drain surveys: check the requirements first

Your designer and the relevant sewerage company should confirm how the proposed work affects the drains and what information they require. Start with the company's current building-over guidance, not another contractor's generic package description.

For example, Thames Water and United Utilities each publish their own processes. Use the guidance for the company responsible for the sewer at your property.

United Utilities’ March 2026 guidance says it does not provide sewer-location or CCTV services. Ask who must commission the inspection and who will accept its results. Do not pay for a private package until those responsibilities are clear.

Sources: Thames Water; United Utilities; United Utilities.

Send your designer any drainage search, previous survey or plan that you hold. Public sewer records can help identify known assets, but Thames Water warns that some sewers and lateral drains may not be recorded.

Ask whether the next step is a records search, tracing or mapping, a condition survey, or a combination. Paying for a camera inspection does not by itself confirm where every sewer is or provide permission to build.

Sources: Thames Water.

Ask the recipient to confirm the report and drawing requirements, then include those in the contractor's quotation request. Clarify whether inspection is needed before work, after work, or at both stages. Do not assume the cheapest advertised CCTV package covers the whole process.

If the work or design changes, ask whether the agreed evidence is still sufficient before booking a repeat survey.

• The sewer or pipe sections to be inspected and identified on the plan.
• The required report format and any condition-coding requirement.
• Any tracing, measured depths, drawing scale or file format requested.
• Which stage of the building work each inspection relates to.
• Who will review the report and what they need to see.
• How inaccessible or incomplete sections should be handled.

Sources: Thames Water; United Utilities.

Ask for a quotation that separates the camera survey, mapping, any cleaning needed for access and the written report. Confirm the total including VAT and any charge for a return visit.

An application or approval fee is not necessarily the contractor's inspection fee. Check each company's current charges and what they include. We do not give a single UK build-over price because the process and work can differ.

Sources: Thames Water; United Utilities.

Approved Document H concerns drainage and waste disposal in England. It should not be presented as one set of building rules for the whole UK.

Check the relevant building-control and sewerage requirements for the property's location. A CCTV report records inspection findings; it does not replace consent, design advice or a decision from the relevant authority.

Sources: Approved Document H.

• Confirm which sewerage company is responsible and obtain its current requirements.
• Send the contractor the recipient's requested report and drawing specification.
• Agree the pipe sections, access arrangements and permitted work.
• Check whether pre-work and post-work inspections are needed.
• Separate survey, mapping, clearance and application charges.
• Agree how incomplete access will be reported and charged.
• Arrange the report review before relying on it for the building work.

Find and check a drainage contractor when you are ready to ask for quotes.