Drainage and septic tanks
What should you ask if an inspection chamber is inside the house?
Ask whether it was lifted, whether it smells, and whether it is still the live drain. An internal chamber is a maintenance burden and sometimes a sign of an altered layout. A home survey can note the cover. It does not guarantee the seal, and it does not camera the run. Building regulations for drainage apply to work that was done. The survey does not retrieve the approval.
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?
Covers in kitchens and extensions fail when the seal is dry or the cover was screwed down under vinyl. The surveyor may not flood the room to test the seal. A smell on the day is a finding. No smell on a cold day is not a pass. Tell the solicitor if the chamber suggests a drain was built over.
A builder quoting a new floor should include the cover, not tile over it. There is no RICS price for moving a chamber. Moving a drain is a drainage job with building control implications, not a survey extra. The surveyor noting a cover in the kitchen has not traced where that drain goes and has not proved the outfall.
What should you ask your surveyor?
- Was the cover lifted, and was the chamber live?
- Is the cover sealed, or is it a sheet of plywood?
- Do you think the drain continues under the extension?
What are the typical next steps?
- Do not tile over a live chamber.
- If you need the route known, use a survey or a camera, not a guess from the cover.
- Ask the solicitor about build-over if the extension sits on the line.
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
Is an internal cover always a defect?
It is a feature that must remain accessible. It is a defect if it leaks, smells or is buried. The survey should say which.
Does a pump in a basement extension replace a chamber?
A pump is a different system. The survey did not test it. Ask where it discharges.