Drainage and septic tanks

What should you ask about emptying records if two houses share a septic tank?

Ask who empties it, how the cost is split, and whether you will become jointly responsible. GOV.UK says you are the operator if you own a property that uses the system, and that properties sharing a system are jointly responsible. Invoices show whether anyone has actually been maintaining it. The survey does not read those invoices.

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 shared tank is a practical problem as well as a legal one. The cover may be on next door’s land. The surveyor may not have had access. Joint responsibility, in the GOV.UK wording, does not tell you the percentage in a private deed. Your solicitor asks for the deed, the invoices and the access. The surveyor tells you whether they could see the tank and any obvious defect.

If there are no invoices, you do not know whether the tank has been emptied or the plant serviced. That is a reason to ask, not a reason to invent a yearly cost. Contractors price emptying from volume and distance. Get a quote after you know what the tank is. Do not treat a neighbour’s handshake as the rule the binding rules describe.

What should you ask your surveyor?

Could you see the shared tank, and on whose land is it?
What could you not inspect because access stopped at the boundary?
What maintenance did you see evidence of, if any?

What are the typical next steps?

Ask the solicitor for the sharing arrangement and the invoices.
If access was refused, decide whether you need a second visit before exchange.
Do not agree to fund a new plant until you know who else must contribute.

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 joint responsibility mean an equal split?

GOV.UK says jointly responsible. The share, if it is not equal, should be in an agreement. Ask the solicitor. Do not assume half.

Can you disconnect and install your own tank without asking?

Not as a surprise. You may need consent, building control and a change to the discharge. Ask before you price it as a simple job.