Drainage and septic tanks
The cellar drain rises when the kitchen is used. What has that shown, and what has it not?
It has shown that using the kitchen pushes water to the cellar drain. That can be a blockage, a pump that is not taking the flow, or a connection you did not expect. It has not shown a collapse, because the survey did not camera the pipe. One demonstration is not a graded survey.
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?
Cellars often have a gully or a sump that should not fill because someone washed up. If it does, the surveyor records the timing: the level rose when the sink or the washing machine ran. They do not jet the pipe, and a visual home survey does not include a camera unless that extra was agreed. Approved Document H is not a diagnosis. Do not write “collapsed sewer” because the water came up. Silt, a stuck flap, a failed pump, and a broken pipe can look alike from the top of a gully.
Tell a drainage firm exactly what rose and which fitting you used. If a pump is in the cellar, say whether it had power. A camera, if they recommend one, is their report. Do not convert their notes into RICS ratings or into grades this survey never used. The damp on the cellar wall may be from this backup, from groundwater, or from both. The survey should not pretend one visit separated them. Until the pipe is seen from the inside, you know there is a link between the kitchen and the cellar drain. You do not know the repair.
What should you ask your surveyor?
- Which kitchen fitting made the cellar drain rise?
- Did you see a pump, and was it running?
- Are you stopping short of calling the pipe collapsed?
What are the typical next steps?
- Do not keep discharging appliances into a drain that is already rising.
- Give a drainage firm the sequence the survey saw.
- Do not buy a camera grade the report does not contain.
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 this the same as a cellar that is damp on a dry day with no one using the sink?
No. Timing against the kitchen is the clue. Damp with no link to a fitting is a different note.
Does a smell in the cellar prove a broken pipe under the floor slab?
No. It proves a smell. The survey did not camera under the slab.