Septic Tank Sewage Discharges

What is a Septic Tank?

Septic Tanks offer a great solution for households that are not connected to the local sewer network. They ensure that household wastewater is processed and disposed of safely and efficiently, without harm to the local environment.

How Do Septic Tanks Work?

A septic tank is a self-contained wastewater treatment system that breaks down waste received from a nearby property.  The septic tank helps to biologically decompose the waste before safely discharging it into the local environment.  The surplus liquid can then drain naturally into the soil via a soakaway.

Because the waste is being disposed to the environment, it needs to comply with Environment Agency regulations.

The General Binding Rules apply if your septic tank or small sewage treatment plant discharges waste water to the ground.

The General Binding Rules

The Rules were first introduced on 1 January 2015.   They are the regulations and the technical requirements specified by the Environmental Agency as guidance to operators of Septic Tanks.

The operator is the person who has control over the operation of the septic tank or sewage plant (“the system”).   This could be the owner of the system or someone else who uses it (e.g. a neighbouring landowner).  It could also be a person who has agreed to be responsible for the maintenance of the system in a written agreement (e.g. a property tenant).

The General Binding Rules were designed to simplify the regulation of small sewage discharges.  Septic tanks and small sewage treatment plants no longer need to be registered and there is no legal requirement to keep records of maintenance.  However, it is still advisable and good practice to keep records of maintenance.

Conventional septic tank system diagram UK

Key Points for Compliant Septic Tank Operation

  • You can discharge up to 2 cubic metres per day to the ground (e.g. back garden) using either a septic tank or small sewage treatment plant.  The Environment Agency has published a calculator for householders to work out the daily discharge.
  • You can discharge up to 5 cubic metres per day to surface water (e.g. river or stream) but you can only use a small sewage treatment plant not a septic tank.
    Existing septic tanks that discharge to surface water must be replaced or have been upgraded by 1 January 2020.  You will need to replace or upgrade the system before this date if you sell the property.
  • The system must comply with the relevant British Standard that was in force at the time of the installation.  It must also be operated in accordance with the manufacturer’s specification.  Maintenance must be undertaken by a competent person.  Waste sludge must be safely disposed of by an authorised person.
  • Discharges starting on or after 1 January 2015:
    • require both planning permission and building regulations approval for the system;
    • are not permitted if any part of the building that the system serves is located within 30 metres of a public sewer.
    • are not permitted if the discharge could reasonably be made to the foul sewer.
    • will require a permit if the discharge is in or close to designated sensitive areas.

Do Cesspits Need to Comply with General Binding Rules?

A cesspit is a sealed tank and owners do not need to comply with the General Binding Rules or apply for an environmental permit.  However, the cesspit must be maintained and emptied regularly by a registered waste carrier.

Buying and Selling Your Property Issues

  • Providing system information: When a property is sold, the operator must give the purchaser a written notice stating that a small sewage discharge is being carried out.  A description of the waste water system and its maintenance requirements should also be given.
  • Surface water discharge: If you currently have a septic tank that discharges to surface water then the sale will trigger the requirement to replace or upgrade the system.
  • System Inspection: Buyers should satisfy themselves that any system is in good working order and does not cause pollution.  There are likely to be costs involved in engaging a surveyor to inspect the system and ongoing maintenance inspections.  There can be further costs if a septic tank needs to be upgraded or replaced or does not qualify for exemption under the Regulations.
  • System Location: It is important to identify the location of the system and check that there appropriate rights and obligations are in place if the system is located on someone else’s property.

Consequences of Too Much Discharge

If a small sewage discharge is not meeting the General Binding Rules, then the Environment Agency will usually try to provide advice and guidance to help resolve the issue.  However, if this is not successful further enforcement action may be taken.

This note only applies to properties located in England as different requirements apply to properties located in Wales.

Further information can be found at: