Drainage and septic tanks
The distribution-box lid is buried and was not found. What of the soakaway split is still unknown?
How the flow splits toward the soakaway is still unknown. The distribution box is the chamber that divides liquid into the arms of a drainage field, and its lid is buried and was not found. The survey did not open that box, did not see the outlets and did not camera the arms. A split that cannot be seen cannot be called even, blocked or intact. The report records a missing lid. It has not mapped the field. A septic tank and a treatment plant are different, and a cesspool only holds sewage until it is emptied.
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?
After a tank that discharges, a distribution box is meant to share flow so one arm of a soakaway does not take everything. If the lid stays buried, nobody can see cracked pipes, a tilted chamber or an outlet that has silted up. The survey only records what was seen, and the lid was not seen. Guessing that the field is fine because the garden looks green invents a result. The unknown part is everything downstream of the lid that could not be lifted.
Ask the solicitor for a drainage plan and the last emptying or service note. A drainage firm can locate and lift the lid, and can camera the arms, if you need the split known. That is new work. Tell a lender the distribution box was not found and the soakaway split is unknown. Do not invent distances from the house to the field, and do not describe the system as a cesspool merely because a lid was missed. The unseen split stays unseen.
What should you ask your surveyor?
- Was the distribution box opened on this visit?
- Is the way flow splits to the soakaway arms still unknown?
- Did a camera see the pipes beyond the buried lid?
What are the typical next steps?
- Treat the soakaway split as unknown until the lid is found.
- Ask the solicitor for any drainage plan and service notes.
- Instruct a drainage firm if the box must be located and filmed.
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
Does a buried lid prove the tank is a cesspool?
No. A cesspool holds sewage and is emptied, and it has no treatment outflow. A buried distribution-box lid suggests a split that could not be found, not a proved absence of every outlet. A septic tank and a treatment plant are different again. The survey only records what was seen. It has not reclassed the system from a lid that stayed underground.
Was the lid found and opened later in the same visit?
No. The lid is buried and was not found, so it was not opened at any point on this visit. There is no second look hiding in the report. Outlets, silt and the split of flow were not seen. A later search by a drainage firm would be a new instruction. Until then the soakaway split remains unknown.