Selling a house with a septic tank: what you must tell the buyer

Plenty of rural houses sell with septic tanks every week. The ones that stall are the ones where nobody knows what’s in the garden, where it drains or when it was last emptied. Fix that before you list.

What the law says you must hand over (England)

The general binding rules say that if you sell, you must tell the new operator in writing that a sewage discharge is in place. Include:

• a description of the treatment system and drainage system
• the location of the main parts of the treatment system, drainage system and discharge point
• details of any changes made to them
• details of how they should be maintained, and the maintenance manual if you have one
• maintenance records, if you have them

The “operator” is the owner or person responsible for the system. After completion, that’s your buyer.

The TA6 drainage questions

The Law Society’s TA6 Property Information Form asks about drainage in section 11. Its explanatory notes cover cesspools, septic tanks and other private systems under 11.6 and 11.7. Buyers will want to know:

• whether the property is on mains drainage, a private system or both
• whether the system is shared with neighbours, and how running and costs are split
• when it was installed or last replaced or upgraded
• for a cesspool, when it was last emptied (11.7(d))
• for a treatment plant, when it was last serviced (11.7(e))
• whether it discharges to ground or surface water

The notes suggest checking title deeds, shared maintenance agreements, purchase documents, installation certificates, builders’ records and planning or Building Control records.

Your pre-sale checklist

1. Identify the system. Septic tank, treatment plant or cesspit? See our comparison.
2. Find where it drains. Drainage field, ditch, stream, or nowhere (cesspit)?
3. Dig out paperwork. Installation date, manual, Building Control sign-off, any permit or exemption.
4. Gather emptying receipts. From a registered waste carrier.
5. Book an empty and service if one is due. It’s cheap evidence the system works.
6. Consider a survey. See costs below.
7. Write the GBR information pack. The five points above. Give a copy to your conveyancer.

Survey costs

Checkatrade says to ask whether emptying, a CCTV survey and a written report are included. Two surveys with similar names may not cover the same work.

The big one: a septic tank that drains to a ditch or stream

In England, septic tanks must not discharge to surface water. That’s been the position since 1 January 2020. Gov.uk now says such systems must be replaced or upgraded as soon as possible. Read what to do about a discharge to a ditch.

Before the 2020 deadline, gov.uk said that for sales of these properties, responsibility for the replacement or upgrade “should be addressed between the buyer and seller as a condition of sale”. That guidance was written for sales before 2020. Today the work is overdue, so expect the buyer to ask for it done, a price reduction or a retention.

Wales and Scotland

Wales. Natural Resources Wales runs a free registration scheme. Check whether your system is registered and give the details to your buyer. NRW’s rules for discharges differ from England’s.

Scotland. Most small domestic sewage discharges must be registered with SEPA (larger ones and some sensitive areas need a permit). The registration fee for a small sewage discharge is £198.55 (checked October 2026). Ask your solicitor to confirm the registration is in place and what needs updating on sale. We haven’t confirmed SEPA’s transfer process, so check it directly.

Buying instead?

Ask for everything on the checklist above, plus a survey by an independent firm. Check when the system was installed. Gov.uk says a buyer should work out whether it counts as a “new” or “existing” discharge, because different rules apply to systems installed or changed significantly since 2 October 2023.

FAQ: selling with a septic tank

Do I have to tell a buyer about my septic tank?

Yes. In England the general binding rules say that if you sell, you must tell the new operator in writing that a sewage discharge is in place, with a description of the system, the location of its main parts, any changes, how to maintain it and maintenance records if you have them.

Can I sell a house with a septic tank that drains into a stream?

You can sell it, but in England a septic tank must not discharge to surface water and the system will need to be replaced or upgraded. Expect the buyer to raise it. Who pays is a matter for negotiation.

Do I need a septic tank survey to sell?

A survey isn't generally a legal requirement. But it helps you answer the TA6 questions accurately and shows buyers the system works. Checkatrade puts a survey at £250 to £300.

Who pays for the septic tank survey when selling?

There's no fixed rule. Sellers sometimes commission one to get ahead; buyers often commission their own. Agree it through your agents.

Do buyers need a permit to take over a septic tank?

Not if the system meets the general binding rules. If it doesn't, and can't be made to, the operator must apply to the Environment Agency for a permit.

Sources

All links checked October 2026.

1. GOV.UK: General binding rules, small sewage discharge to the ground
2. GOV.UK: General binding rules, small sewage discharge to a surface water
3. GOV.UK: Septic tanks and sewage treatment plants, what you need to do
4. The Law Society: TA6 Property Information Form, 6th edition explanatory notes
5. Checkatrade: Septic tank inspection cost (updated October 2026)
6. Home Septic: Home buyer survey
7. Premier Tech Aqua: Home buyer septic survey
8. Natural Resources Wales: Register your septic tank or small sewage treatment plant
9. SEPA: Septic tanks and private sewage treatment systems