What are the Environment Agency General Binding Rules for septic tanks in the UK?

In England, off-mains domestic drainage is governed by the General Binding Rules (GBRs) set out by the Department for Environment, Food and Rural Affairs (DEFRA) and the Environment Agency under the Environmental Permitting (England and Wales) Regulations.

Prior to 2015, many rural properties discharged effluent from primary settlement septic tanks directly into roadside ditches, agricultural watercourses, or streams. Since 1 January 2020, this practice is strictly prohibited. Property owners with septic tanks discharging to surface water must either replace the tank with a packaged sewage treatment plant, install a compliant drainage field, or connect to the public sewer.

Under Building Regulations Approved Document H2 and Environment Agency guidance, ground infiltration drainage fields must maintain strict statutory clearance distances: at least 10 metres from any watercourse, at least 50 metres from any potable water abstraction borehole or spring, at least 15 metres from any residential dwelling, and at least 7 metres from property boundaries.

For permit-free operation, domestic discharges must not exceed 2,000 litres per day into ground or 5,000 litres per day into watercourses. Daily discharge is calculated using British Water Flows and Loads formulas based on design bedroom capacity (typically (Bedrooms + 2) × 150 litres/day).

Section 3 of the Law Society Property Information Form (TA6 Form, 4th Edition) contains mandatory questions requiring the vendor to declare the drainage system type, date of installation, discharge location, maintenance frequency, and whether the system complies with the 2020 General Binding Rules.

If a property fails GBR compliance, the buyer's conveyancer must report the defect to the mortgage lender. Lenders will refuse to issue mortgage funds unless the seller agrees to upgrade the system prior to completion or a formal financial retention (£7,000–£12,000) is held in solicitor escrow.