If you have a septic tank or small sewage treatment plant in England, it’s governed by the Environment Agency’s General Binding Rules. These are the conditions that let you discharge treated wastewater without applying for a permit — as long as you meet them all. This guide explains the parts that matter to most homeowners.

This is general compliance and trades information, not legal or conveyancing advice. For a formal position on a specific property, get it assessed.

The headline: the 2020 rule

The change most people have heard about: since 1 January 2020, you must not discharge from a septic tank directly to a surface water — a stream, river, ditch, canal or any other watercourse.

If your septic tank does this, it needs to be replaced or upgraded. The two usual routes are:

1. Replace the septic tank with a sewage treatment plant (which produces effluent clean enough to discharge to a watercourse within limits), or
2. Install a drainage field so the discharge goes to the ground instead.

If you’re selling a property with a non-compliant tank, this must be resolved as a condition of the sale.

Discharging to the ground

If your system discharges to the ground through a drainage field, the binding rules require that:

• the discharge is no more than 2 cubic metres per day;
• the drainage field is built to the proper standard (BS 6297);
• it is not within a groundwater Source Protection Zone 1;
• it keeps the required distances from watercourses, boreholes and buildings.

Discharging to a surface water

If your system discharges to a watercourse, the binding rules require that:

• it comes from a sewage treatment plant (not a septic tank);
• the plant meets the relevant standard (BS EN 12566);
• the discharge is no more than 5 cubic metres per day.

Above these volumes, or in sensitive locations, you need a bespoke permit rather than relying on the binding rules.

Your ongoing duties

Whichever system you have, you must:

• maintain it and keep it in good working order;
• have it emptied by a registered waste carrier and keep the records;
• not cause pollution;
• connect to the public sewer instead if one is available and connection is reasonably practicable.

Check where you stand

Our free compliance checker walks you through these rules in a couple of minutes and tells you, in plain English, whether your setup is likely compliant and what to do if not.

Sources: GOV.UK — General binding rules: discharge to a surface water · GOV.UK — General binding rules: discharge to the ground