Build Over Agreement Checker

The 3 m rule and Approved Document H4

In England, Approved Document H covers drainage and waste disposal, including provisions relevant to buildings near drains and sewers. Separately, sewerage companies publish their own build over policies. A distance of 3 m from a public sewer is commonly used by companies when deciding whether an application is required, but the exact test and measurement must be checked with the company responsible for the sewer.

If the proposed work is close to a public sewer, the sewerage company may require information about the foundations, the position and condition of the pipe, access for future maintenance or an alternative design such as diversion. Requirements depend on the particular sewer and proposal.

Approved Document H cited here applies in England. Requirements elsewhere in the UK should be checked against the rules and sewerage arrangements applying in that nation.

Why the October 2011 transfer matters

On 1 October 2011, most existing private sewers and lateral drains within the transfer arrangements in England and Wales became the responsibility of sewerage companies. A drain serving one property within that property’s boundary generally remained private, so the status of an individual pipe should be checked rather than assumed from its age alone.

That change matters for build over agreements. A pipe that was private before 2011 may now be the responsibility of a sewerage company. Older work may therefore have been carried out under different ownership or consent arrangements. For work proposed now, check the pipe’s current status and the sewerage company’s current requirements.

Scotland and Northern Ireland have different arrangements for sewer ownership and adoption, so the 2011 transfer does not apply in the same way.

What water companies typically ask for

Application routes and technical requirements vary between sewerage companies. Depending on the proposal, the company may ask for drawings, foundation details, sewer records, CCTV survey information or other site-specific evidence. Some application routes include or require pre-construction and post-construction CCTV surveys.

Pipe size, sewer type, depth, location and the nature of the development can affect whether a standard build over route is available. Some proposals may require a sewer diversion or further technical assessment instead. Check the current published requirements of the sewerage company responsible for the site before commissioning supporting work.

Using the checker

The checker asks questions about the proposed work and the drain or sewer near it. It provides guidance on points to check with the relevant sewerage company. It does not classify the pipe, confirm that an agreement is required or give permission to build.

You can print the result or save it as a PDF from your browser. If you want a survey to support an application, the result can pre fill an enquiry.

We can help with build over CCTV surveys before and after construction, and with drain mapping where the position of the sewer needs to be confirmed.

Surveys that support an application

A pre construction CCTV survey records the condition of the sewer before work starts. It shows visible internal surfaces, including joints, cracks and existing defects. It cannot see through deposits or detect every defect, and the report contents depend on the agreed specification.

A sewerage company may also require a post-construction survey so the condition can be compared with the earlier record. Any action required where a defect is identified is for the sewerage company and the parties involved to determine.

Where the sewer cannot be accessed from existing manholes, a dye test can help confirm connections. For a broader picture of the drainage, a drainage survey may be more suitable.

Costs and timescales

Water companies set their own application fees, and these vary. Some charge a fixed fee, others charge based on the size and complexity of the sewer. A survey, drawings and any foundation design are separate costs.

Timescales depend on the sewerage company, the application route, the information supplied and whether further investigation or design work is required. Check the company’s current published timescales when planning the work.

Prices require a real quote. The drivers include the length of sewer to be surveyed, the number of manholes, access arrangements and whether a post construction survey is also needed.

What to do if you are unsure

Start by finding out whether a public sewer is near the proposed work. Sewer records show the recorded position, but they may not establish the exact line on site. CCTV, sonde tracing or other site investigation can help establish the pipe’s route and depth where this is needed.

Then contact the sewerage company responsible for the sewer. Ask whether an agreement is needed, what information they require, and whether they need a survey before or after the work. Keep the response with your project records.

If work has already been completed without an agreement, contact the sewerage company responsible for the sewer and explain what has been built. Retrospective application routes exist in some circumstances, but the evidence and any remedial action required depend on the company and the site.