commercial law sudbury essex

Septic Tanks and the discharge of waste

If you own a property with a septic tank or are thinking of selling or buying one, then you need to be aware of the relevant regulations. Most domestic discharges of sewage will be exempt from the Environment Agency’s (EA) permit regime, as long as they comply with their General Binding Rules (GBR). Current GBR’s were introduced at the beginning of 2015 and the operator of the system (the home owner or the tenant) is responsible for complying with them. There are slightly different rules depending on whether you have a septic tank or a small sewage treatment plant and whether you discharge to the ground or to surface water.


  • You may discharge up to two cubic metres per day to the ground, or 5 cubic meters to flowing surface water if you have a sewage treatment plant.
  • The system must comply with the relevant British Standards in force at the time of installation and be operated and maintained properly
  • A discharge starting after the 1st January 2015 needs building regulations approval and probably planning permission, and will require an EA permit if the discharge is in or close to a designated sensitive area or Groundwater Protection Zone 1.

New septic tanks or treatment plants are unlikely to be permitted if the building it serves is less than 30 metres from the public sewer and for a new shared system that distance is multiplied by the number of properties served.

Most septic tanks discharge to a drainage field through perforated pipes but some older systems discharge to a water course. This has long been a questionable practice and from the 1st January 2020, there will be a legal obligation to cease. This could mean either creating a drainage field if the ground conditions and EA allow, or installing a small sewage treatment plant which could discharge to the surface water.

If you are buying a house with a septic tank, an important question will be whether it is complying with the GBR’s, or require upgrading to a more expensive treatment plant. An inspection by a qualified engineer will be crucial. As the seller, you may need to prepare for renegotiation if a problem is found.

As with all things, there is a huge amount of information on the internet, not all of it helpful. The EA website contains all of the rules in more detail than most people would want, including links to designated sensitive areas.

Although the deadline for upgrading non-compliant systems is fast approaching, enforcement is unlikely to be an EA priority unless there are complaints from the public or significant pollution incidents.

In practice, the policing of the regulations is more likely to be down to conveyancers acting for buyers of these properties, whose drainage systems will need upgrading as and when they are sold.

Nonetheless, if you are aware that your septic tank outfalls to a ditch or pond, you would be well advised to take action now before a sale of the property. Dealing with these things during the sale just adds complexity to what is often a fairly anxious time.

Written by Matthew Stamp – Bates Wells & Braithwaite – 01787 880440

Matthew Stamp

Matthew joined the residential property department at Bates Wells & Braithwaite in 1986.

He studied geography and environmental science at the University of Manchester before returning to Suffolk where a change in direction saw him join the firm.

He is well known to local landowners and devotes much of his spare time to conservation issues having worked in the past for Groundwork Trust and Suffolk Wildlife Trust. He also enjoys walking, travelling and photography in his spare time.