Drainage and septic tanks
There is one old invoice for emptying the septic tank at this house. What does it not prove?
It does not prove the tank is sound now, and it does not prove the discharge meets the rules. One invoice for one house is a record that someone emptied something on that date. It is not a survey, not a shared-tank agreement, and not a camera of the outfall.
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?
Read the date, the address, and what was emptied. An invoice from years ago says the system once needed a tanker. It does not say whether the lid can be found, whether the tank is cracked, or where the effluent goes today. In England the general binding rules for small sewage discharges have applied since 2 October 2023. A discharge to ground up to 2 cubic metres a day is through a septic tank or a treatment plant and an infiltration system. A discharge to surface water up to 5 cubic metres a day needs a treatment plant, not a septic tank alone. Wales, Scotland and Northern Ireland differ. The invoice does not measure a daily volume. A cesspool stores sewage and does not discharge. The paper may not even say which of those was emptied.
This is not the question of two houses sharing a tank. Here there is one property and one old bill. Ask the seller for any later invoices and for a plan of the outfall. The home survey does not prove that outfall, and it does not become a binding-rules audit because a bill was in the drawer. Approved Document H does not check the tanker docket. No camera grade was produced. If you need condition, uncover the lid and use someone who understands private drainage. Quote them. Do not turn the age of the paper into a price the survey never wrote.
What should you ask your surveyor?
- What date and what address are on the invoice, and what does it say was emptied?
- Did you see the tank as well as the paper?
- Are you treating this as one house, not a shared system?
What are the typical next steps?
- Ask for any later emptying or service records.
- Do not treat a single old invoice as proof the outfall complies.
- Do not apply English discharge rules to a house in Wales, Scotland or Northern Ireland without checking those countries.
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 recent empty mean the soakaway works?
No. Emptying removes stored sludge. It does not test an infiltration system or prove an outfall.
Is the invoice an EICR or a gas record?
No. It is a tanker bill. Electrics and gas are separate, and this paper tests neither.