If a drain beneath a new building cannot be fully inspected, the survey should record the sections examined and identify exactly where inspection stopped. An incomplete CCTV survey does not demonstrate that the uninspected pipework is defective, but neither does it establish that the inaccessible section is in satisfactory condition.
For developers approaching completion or handover, the important distinction is between a drain that has been inspected and one whose condition remains unknown.
What incomplete coverage means
A CCTV survey records the internal condition of drainage pipework that the camera can reach and adequately view. Its findings only apply to the portions actually examined.
For example, consider a drainage run measuring 30 metres between two inspection chambers. If the camera travels 19 metres before encountering an obstruction, the remaining 11 metres have not been inspected from that direction.
The survey may still provide useful evidence about the first 19 metres. However, a statement that the entire run was inspected would misrepresent the available information.
This distinction becomes particularly important when drainage records are being assembled for building completion, defects management or a proposed sewer adoption.
A Section 104 adoption CCTV survey may form part of the evidence required for an eligible sewer network in England and Wales. The scope, reporting format and acceptability of incomplete coverage depend on the relevant sewerage company’s requirements and the particular development.
Distinguishing access problems from obstructions
Not every incomplete inspection indicates a structural problem with the underground pipe. The reason the camera could not continue should be recorded clearly.
Access is unavailable
A chamber might be covered by temporary construction materials, obstructed by equipment or inaccessible within a completed area. In this situation, the pipe may be capable of inspection once an alternative access arrangement is established.
Where an inspection point has been permanently concealed, the developer may need to review the installed drainage arrangement against the design and applicable requirements.
In England, Approved Document H covers underground drainage and provisions for manholes and inspection chambers. Those provisions provide relevant design context, although they do not establish that a particular incomplete CCTV recording is acceptable for handover.
The camera encounters a restriction
Debris, construction residue, displaced joints, deformation or standing water may prevent the camera from progressing or obtaining a clear view.
These circumstances require different responses. Loose material may need clearing before another inspection, while a suspected pipe defect may require further investigation. A camera that cannot proceed is not, by itself, proof of collapse.
The inspection record should distinguish a confirmed defect from a possible obstruction that has not yet been identified.
Resolving uninspected sections
A practical first step is to compare the recorded survey coverage with the drainage layout. This establishes which runs have been examined, where the inspection stopped and whether another chamber provides access from the opposite direction.
Useful information includes:
- The identification of each relevant chamber and pipe run.
- The direction and measured extent of completed inspection.
- The position and description of any obstruction.
- Whether the camera could view the full pipe circumference.
- Any connections or branches that remain unexamined.
- The proposed action for each unresolved section.
Where the drainage layout is uncertain, drain mapping may help relate accessible chambers and connections to the construction records.
Reinspection from the opposite end may resolve some gaps. Other sections may require obstruction removal, access arrangements or repairs before meaningful footage can be obtained.
What should be recorded before handover?
The final documentation should distinguish completed inspection from unresolved survey coverage. A schedule or annotated plan showing inspected, restricted and uninspected sections is particularly useful when several contractors or development phases are involved.
Where reinspection remains outstanding, the record should identify who is coordinating the next action and which evidence is still required.
For adoption work, the relevant sewerage company’s acceptance requirements must be checked rather than assuming that footage from neighbouring sections is sufficient.
Clear documentation prevents an incomplete inspection from being mistaken for evidence that the entire drainage network has been examined. It also gives the developer a defined starting point for resolving outstanding drainage questions before handover.
