The 1 January 2020 Surface Discharge Ban
Under the General Binding Rules introduced by the Environment Agency under the Environmental Permitting (England and Wales) Regulations 2016, traditional septic tanks that discharge directly into watercourses became illegal on 1 January 2020.
Septic tanks only provide basic primary settlement; they do not aerobically treat sewage. Discharging untreated effluent into a seasonal ditch, stream, or brook causes severe biological contamination and is an offence under the Environmental Permitting Regulations.
Crucially, the rules abolished all historical 'grandfather rights'. It is no defense that a septic tank discharge existed lawfully since Victorian times or pre-dated the 1983 regulations.
Seller's Mandatory Disclosure Duty Under Rule 11
Under General Binding Rule 11, anyone selling a property with a septic tank or small sewage treatment plant has a strict legal obligation to provide the buyer with a written notice containing:
• A full description of the wastewater treatment system and its drainage field layout.
• The exact location of the septic tank, inspection chambers, and discharge point.
• Required maintenance instructions and maximum volume capacities.
• Full maintenance logs and desludging receipts for the preceding 12 months.
How to Resolve a Non-Compliant Septic Tank During a Property Sale
If a property survey reveals an illegal surface discharge, conveyancers use three standard commercial solutions:
1. Seller Upgrades Before Completion: The seller contracts a specialist drainage contractor to install an EN 12566-3 compliant sewage treatment plant (£8,000 to £14,000 + VAT) prior to legal completion.
2. Retention of Sale Funds: The buyer's solicitor retains an agreed sum (£10,000 to £15,000) from completion monies in escrow, to be released to the buyer upon completion of the upgrade post-sale.
3. Price Renegotiation: The agreed purchase price is reduced by the estimated replacement cost, and the buyer assumes legal responsibility for the replacement.