Drainage and septic tanks
Where a pitch-fibre pipe emerges under a patio slab it is oval rather than round. What length of oval pipe beyond that point was not camera-surveyed?
Whatever length of oval pipe lies beyond that exposed end was not camera-surveyed. Where the pitch-fibre pipe emerges under a patio slab it is oval rather than round, which the survey can describe at that visible end. Oval pitch fibre often means the pipe has squashed, but the inspection has not measured how far that shape continues. No camera was sent along the drain. The finding stops at the pipe that could be seen.
Last reviewed 24 October 2026. Written for buyers in England and Wales unless this answer says otherwise. No named surveyor has signed this page. It is general guidance, not a report on your house, and not legal advice.
What is the fuller explanation?
Pitch fibre is a pipe material that can deform, so a round bore becomes oval and the flow is pinched. Seeing that oval under the edge of a patio tells you about the piece in view. The run under the slab, and the run beyond it, stayed in the ground. A chamber elsewhere, if one was lifted, still does not film the length between. The home survey records the deformed end. It does not become a CCTV survey by describing it.
If you need the length known, instruct a drainage firm to camera the run from a chamber, with the seller's agreement, and ask them to relate the film to this oval end. Tell the solicitor the survey has not measured the deformed length. Do not lift patio slabs on a guess. The home survey only records the pipe it could see.
What should you ask your surveyor?
- Was the oval shape recorded only at the exposed end under the patio?
- Was the length beyond that end left without a camera survey?
- Did you stop short of saying how far the deformation runs?
What are the typical next steps?
- Limit the note to the oval pipe that could be seen.
- Do not guess the length still buried beyond the patio.
- Instruct a camera survey if that hidden length must be known.
Costs vary with the building and with who you instruct. Where this page does not cite a published figure, ask the surveyor, a relevant specialist, or your solicitor for a written quote. Do not treat a forum average as the price.
Also asked about this
If the patio has not sunk, is the rest of the pipe round?
No. A level patio does not show the bore of a buried pipe. Only the emerging end was seen, and it was oval. Nothing beyond that point was camera-surveyed. The length of oval pipe under and beyond the slab remains unknown. The survey stopped at the pipe it could see.
Does water sitting in a chamber prove the whole run is crushed?
Not by itself. Standing water is a chamber observation. It does not measure how much of the pitch-fibre run is oval. The survey did not film that length. Water in a chamber is not a camera survey of the pipe under the patio. The deformed end is the only shape the home survey recorded.