Drainage and septic tanks
A reed bed is said to follow the septic tank and it was not walked. Has the survey sampled the discharge?
The discharge has not been sampled. A reed bed is said to follow the septic tank, and the bed was not walked, so the plants, the outlet and any liquid leaving the system were not seen. A septic tank and a treatment plant are different, and a cesspool only holds sewage until it is emptied. A reed bed is a further stage people describe after a tank. The survey records the claim and the unwalked bed. It has not tested water quality and has not decided the system works.
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?
A septic tank settles sewage and should discharge onward. A reed bed, if it really follows, is a planted area that liquid may cross after the tank. Walking it would show whether the bed exists, whether it is waterlogged and where it overflows. None of that was done. Sampling the discharge would mean taking the liquid at a proper point and having it examined. The survey did not take that sample. A description from the seller is not a test result, and the survey only records what was seen.
Ask the solicitor for emptying records, any permit or exemption, and a plan that shows the tank and the reed bed. A drainage firm can walk the bed and sample the discharge if you need those facts. That work is not this report. Tell a lender the bed was not walked and the discharge was not sampled. Do not describe the system as complete because someone said the reeds come next. The tank that was seen is not a laboratory result.
What should you ask your surveyor?
- Was a sample taken of liquid leaving the tank or the bed?
- Was the reed bed walked so the outlet could be seen?
- Has water quality been decided, or only a seller's description recorded?
What are the typical next steps?
- Treat the reed bed and the discharge as unseen and untested.
- Ask the solicitor for permits, exemptions and emptying records.
- Instruct a drainage firm if the bed must be walked and sampled.
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 a reed bed the same vessel as a cesspool?
No. A cesspool holds sewage and is emptied. It is not a reed bed, and it is not the same as a septic tank or a treatment plant. The survey was told a reed bed follows the septic tank and did not walk it. The survey only records what was seen. It has not reclassed the system as a cesspool or sampled anything.
Can green plants be treated as a clean discharge?
No. Plants, even healthy-looking reeds, are not a test of the liquid. The bed was not walked and the discharge was not sampled, so quality stays unknown. The survey has not decided the outflow meets any consent. Pass service papers to the solicitor as documents, not as a result of this visit. A sample would be new work.