England: the general binding rules explained

If you run a septic tank or small sewage treatment plant in England, you don't need a permit as long as you meet the general binding rules that apply to you. Here's a summary of the Environment Agency guidance.

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Which rules apply depends on when your discharge started

  • Before 1 January 2015: the rules that apply to all discharges.
  • 1 January 2015 to 1 October 2023: plus the additional rules for those discharges.
  • On or after 2 October 2023: plus the rules for new discharges.

A discharge counts as new if you start one, switch from surface water to ground, move the discharge point more than 10 metres, or increase it by more than 2 m³ (2,000 litres) a day. Replacing the tank on its own, without those changes, keeps you in your existing category.

Key rules for discharges to ground

Diagram of how a septic tank works: wastewater enters a two-chamber tank, solids settle as sludge, fats float as scum, and settled liquid flows out to a drainage field where it soaks into the soil
How a septic tank works Tap the diagram to open it full size.
  1. Wastewater from the house enters through a dip pipe.
  2. Fats and oils float to form a scum layer.
  3. Solids sink to form sludge, which is removed when the tank is emptied.
  4. Settled liquid passes into the second chamber, then out through the outlet dip pipe.
  5. Effluent spreads through perforated pipes in gravel trenches (the drainage field) and is treated as it soaks into the soil.
  • No more than 2 m³ (2,000 litres) a day, and only domestic sewage.
  • Use a septic tank or small sewage treatment plant with a drainage field. A soakaway designed for rainwater and installed after December 2007, a well or a borehole doesn't comply.
  • The system must meet the British Standard in force when it was installed. Current ones are BS EN 12566 for tanks and plants, and BS 6297:2007 for drainage fields. Systems installed before 1983 are exempt from this point only.
  • It must have enough capacity, sized using British Water's Flows and Loads guidance if it was installed after 1 February 2006.
  • It must not be in a groundwater Source Protection Zone 1 (except SPZ1c). If it is, you need a permit.
  • It must be regularly emptied by a registered waste carrier, usually at least once a year or as the manufacturer recommends.
  • It must be repaired or replaced if it's not in good working order.
  • New discharges can't be in ancient woodland, or in or within 50 m of a SAC, SPA, Ramsar site or biological SSSI.
  • For a single property, you can't use the rules if a public foul sewer is within 30 m of the property boundary.
  • New discharges also can't be within 50 m of another discharge under the general binding rules.

Full detail: GOV.UK: General binding rules – small sewage discharge to the ground.

Discharges to surface water (ditches, streams, rivers)

Diagram of how a sewage treatment plant works: primary settlement, an aerated biological stage fed by an air blower, final settlement with sludge return, and discharge of treated effluent
How a sewage treatment plant works Tap the diagram to open it full size.
  1. Primary settlement: solids settle out as sludge.
  2. Aeration: an electric blower pumps air into the middle chamber so bacteria can break down the waste.
  3. Final settlement: remaining solids settle and are returned to the first chamber.
  4. Treated effluent goes to a drainage field, or to a watercourse where your registration or permit allows.

Effluent from a septic tank must not go to surface water. Only a small sewage treatment plant can discharge to surface water under the rules, with a limit of 5 m³ a day. If your septic tank currently discharges to a watercourse, you need to replace it with a treatment plant, divert it to a drainage field, or connect to the mains sewer. The deadline for existing discharges was 1 January 2020, and if it's still happening you should act now. GOV.UK: General binding rules – small sewage discharge to a surface water.

Selling a property

You must tell the buyer in writing that a sewage discharge is in place, including a description of the system, where its parts are, any changes made, and maintenance records. If the system doesn't comply, agree before completion who'll put it right.

If you can't meet the rules

You must connect to a public foul sewer, change your system so it complies, or apply to the Environment Agency for a permit.

Frequently asked questions

Is the 2020 septic tank rule still in force?

Yes. In England septic tanks must not discharge to surface water. The 1 January 2020 date was the deadline for existing discharges, and if yours still discharges to a watercourse, you should fix it as soon as possible.

Do I need to register my septic tank in England?

No. There's no registration in England if you meet the general binding rules. If you can't, you need an environmental permit from the Environment Agency.

How often must I empty my septic tank in England?

Before the sludge goes beyond the tank's capacity, which the guidance says should be at least once a year or in line with the manufacturer's instructions. Use a registered waste carrier.

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