MySepticCheck

Seller guide · England

Selling a house with a septic tank

A practical guide to the information you should gather before conveyancing gets complicated.

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What a seller needs to know

If a property in England uses a septic tank, sewage treatment plant or another small sewage system, the person responsible for it is its operator. When the property is sold, official guidance says the seller must give the new operator written information about the sewage discharge.

This applies whether the system serves one property or is shared with neighbouring properties. The rules differ in Scotland, Wales and Northern Ireland.

Information to prepare for the buyer

The written information should include:

  • a description of the treatment and drainage system
  • the location of its main parts and discharge point
  • details of any changes made to the system
  • the maintenance instructions or manual
  • maintenance records, if they are available

Emptying receipts, service records, installation documents and photographs can also help explain what is present, even though the exact evidence available will vary from property to property.

Check where the system discharges

Discharge to the ground A septic tank or treatment plant must discharge through a drainage field that meets the applicable rules. A soakaway designed only for rainwater is not a drainage field.
Discharge to surface water A septic tank must not discharge directly to a river, stream, ditch or other surface water. A small sewage treatment plant is required for a qualifying discharge to surface water.

If a septic tank discharges directly to surface water, the official guidance says it must be upgraded. During a sale, buyer and seller should agree who will carry out the work as a condition of sale.

Seller timeline: from marketing to completion

Before marketing Identify the system and where it discharges. Gather plans, manuals, emptying and service records, and note anything you cannot yet confirm.
During conveyancing Share the system details and available records with your conveyancer for the buyer. Raise missing records, shared arrangements or discharge concerns early, and arrange specialist advice if needed.
Before completion Make sure the new operator receives the required written information about the system and discharge. If an upgrade is needed, agree with the buyer who will carry it out as a condition of sale.

A sensible order for getting ready

  1. Identify the type of system and whether it is shared.
  2. Locate the tank or plant, drainage field and discharge point.
  3. Gather maintenance, emptying and installation records.
  4. Check for missing information, signs of a problem or a direct discharge from a septic tank to surface water.
  5. Consider a septic tank inspection or survey and seek legal advice where the arrangement is unclear.
  6. Give the buyer the required written information.

Organise your seller information

MySepticCheck helps you bring the information you have into one clear record, identify gaps and create a Seller Information Pack.

Start my check Read the rules explainer

Official guidance

Read the Environment Agency's septic tank overview on GOV.UK, plus the detailed rules for discharges to the ground and discharges to surface water.

Guidance reviewed 3 September 2026. This page is for properties in England. MySepticCheck is an information and readiness tool, not a compliance certificate, survey, physical inspection or legal or environmental advice.