Risk & reassurance

What are the General Binding Rules?

The Environment Agency rules every septic tank must meet — and what the 2020 watercourse ban means for you.

The short answer

The General Binding Rules are the Environment Agency conditions a small sewage system must meet to operate without an individual permit. The key change: since 1 January 2020, a septic tank may no longer discharge effluent directly to a watercourse such as a river, stream or ditch. If yours does, you must connect to a public foul sewer, replace the tank with a small sewage treatment plant, or divert the discharge to a drainage field — generally within around 12 months of identifying the problem. The rules also require regular emptying by a registered waste carrier and written disclosure to a buyer when you sell.

The General Binding Rules are the statutory gate that sits behind every septic tank decision. Failing them can mean an unlimited fine, so it pays to know exactly what they require.

The rules at a glance

What changed on 1 January 2020

Before 2020, many older septic tanks discharged settled effluent straight into a watercourse. Under the General Binding Rules, that direct discharge is no longer allowed — a basic septic tank does not treat effluent to a high enough standard for surface water. If your tank discharges to a stream, river, ditch or other watercourse, you must take one of the compliant routes below.

What counts as a watercourse: a river, stream, canal, lake, ditch or similar surface water. Discharge to ground via a properly designed drainage field is different and is permitted under the ground rules, subject to suitable ground conditions.

The three routes to compliance

  1. Connect to the public foul sewer where one is reasonably accessible.
  2. Replace the septic tank with a small sewage treatment plant (certified to BS EN 12566-3) that treats effluent to a standard suitable for discharge to surface water.
  3. Install a drainage field (designed to BS 6297) so the discharge goes to ground rather than to the watercourse, subject to percolation testing.
Timescale: the Environment Agency expects you to have plans in place to put things right within a reasonable timescale, usually around 12 months once the issue is identified — and sooner if a sale is in progress.

Need to make a tank compliant?

We'll match you with a registered septic tank specialist who assesses your discharge against the General Binding Rules and quotes the right compliant solution for your site.

Get matched with a specialist Browse all guides
Free to be matched. You agree any price with the specialist directly.

Frequently asked questions

What are the General Binding Rules?

They are the Environment Agency conditions a small sewage discharge must meet to run without an individual permit — covering where you can discharge, maintenance, and disclosure when selling. Since 1 January 2020 a septic tank cannot discharge directly to a watercourse.

My septic tank discharges to a stream — is that legal?

Not under the General Binding Rules. Since 1 January 2020 direct discharge to a watercourse is banned. You must connect to a sewer, fit a treatment plant, or divert to a drainage field, generally within around 12 months.

What happens if I ignore the rules?

Non-compliance can lead to an unlimited fine and responsibility for cleaning up any pollution. It also commonly stalls a house sale, because the buyer's solicitor will want it resolved first.

Sources & further reading

Figures on this page are typical UK ranges drawn from published sources and depend on your specific site. They are guidance, not a quotation.