Drainage and septic tanks
A pipe the seller calls grey water discharges into a ditch. Has that flow been sampled?
No. The flow has not been sampled. A pipe the seller calls grey water, discharging into a ditch, was recorded as a visible outlet. The survey did not test the liquid, did not trace the pipe back to a particular fitting, and did not decide the flow is only from baths and basins. A seller's name for the pipe is not a sample result. The visit has not decided the discharge is clean, foul, or permitted.
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?
Grey water is a loose household phrase for used water from sinks and baths, as distinct from the toilet. Pipes are not labelled by the surveyor's nose, and a ditch will not sort the sources. The same outlet could receive wash water, a wrongly connected foul branch, or both. Without a trace and a sample, those possibilities stay open. The inspection recorded the discharge point it could see. It did not follow the pipe through the ground.
Ask the solicitor what drainage searches and any consents say about discharges from this property, and do not let the seller's label settle them. A drainage firm can trace and sample if you instruct that. The survey did not. Tell a lender the ditch outlet was seen and not tested. Do not describe the flow as proved grey water. The survey has not judged the discharge lawful, and it has not measured the outlet against any other feature.
What should you ask your surveyor?
- Was the ditch outlet seen but not sampled?
- Did the survey trace the pipe back to a fitting?
- Is the seller's grey-water label recorded as a label, not a test?
What are the typical next steps?
- Treat the ditch discharge as unsampled.
- Ask the solicitor what searches say about outfalls from the property.
- Do not describe the flow as proved grey water.
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
Could the same pipe also carry water from a toilet?
It could, and this visit did not rule that out. The pipe was not traced and the flow was not sampled. A seller's description does not close the question. Until a drainage inspection follows the branch, foul water and wash water remain possible sources. The survey has not chosen between them.
Does a clear ditch downstream show the discharge is harmless?
No. Clear water on one day is not a sample and not a consent. The survey did not test the liquid and did not walk the whole ditch as a laboratory exercise. Appearance downstream can change with weather and with what enters upstream. The outlet stays untested.