Regulation of Septic Systems & Sewage Treatment Systems in the U.K.
Onsite / Off-Grid Wastewater Treatment Regulations Summary for UK Septic Tanks & Soakaway Beds

Onsite wastewater regulations in the U.K.

Summary of off-grid sewage treatment system regulations in the U.K.

This article describes the three off-grid sewage handling & treatment options in the U.K., the requirement for an EN 12566 Certificate for larger treatment systems, the EN 12566 wastewater treatment system categories or types, limitations on or prohibitions on the use of cesspools, and regulations addressing the disposal of septage in the U.K. as well.

Septic System & Off-Grid Onsite Septic System & Wastewater Treatment Regulations in the U.K.

Three Off-Grid Sewage System Options in the UK: updated UK Septic System Regulations

Maureen Webb wte-ltd.co.uk

In the UK there are three options for off-mains sewage systems:

1. Septic Tank connected to an onsite soakaway bed or similar effluent disposal field
2. Sewage Treatment Plant
3. Cesspool (only in England and Wales. Cesspools are banned in Scotland)

1. Septic Tank Requirements for Off-Grid Wastewater Treatment in the UK

These are anerobic [anaerobic] settlement tanks that settle out the solids, forming  a sludge layer at the bottom of the tank and a floating crust on the top of the effluent.

The liquid waste between these two layers is discharged to a soakaway drainfield, subject to Environment Agency or SEPA (in Scotland) permission. The majority of sites in the UK fail the mandatory

soakaway tests, making septic tank installations impossible in many areas.

2. UK Sewage Treatment Plant Requirements

These are aerobic tanks which treat the sewage effluent to a much higher standard of quality than a septic tank. The final effluent is allowed to be discharged directly to a watercourse or ditch, or to a soakaway drainfield, subject to Environment Agency or SEPA (in Scotland) permission.

3. Cesspools for Wastewater Collection in the UK

In the UK, cesspools are sealed underground holding tanks which offer no actual treatment of the sewage and have no effluent outlet.

Cesspools need to be emptied by tanker on a regular basis.

Cesspools are banned in Scotland as they are not sustainable and very expensive to operate.

UK Septic System Rules and Regulations - EN 12566 Certification

All septic tanks and sewage treatment plants up to 50 persons must be registered and permitted in the UK. The Environment Agency operates the registration scheme and issues their Permits and Exemptions. In order to qualify for this acceptance, the systems must have an EN 12566 Certificate under the EPP2 (Environmental Permitting Programme Phase 2) regulations.

The EN 12566 certificate ensures that the tank has been structurally tested for strength and water-tightness and, in the case of sewage treatment plants, performance tested for water quality for 38 weeks at an independent EN Test Centre.

Cesspools must have been structurally tested for strength and be water-tight. They must also have a high level alarm.
From July 1st 2013, all tanks will need to be CE marked in addition to the above under the Construction Products Directive. In order to have the CE mark, the tanks must have an EN 12566 Certificate.

2020 Septic System Regulations Updated in 2020

Watch out: beginning in 2010

No septic systems can discharge into a waterway or body of water. Such systems must be replaced with a system compliant with British Standard BS EN 12566-3 and with amended BS6297 2007 that requires that effluent be redirected to an absorption system or soakaway or drasinfield.

In Scotland septic systems must comply with the Scottish SEPA, but systems in use and serving fewer than 50 people since 1 April 2006 can be registered and licensed.

In Wales septic systems and sewage treatment plants must be registered with the Wales Department of Natural Resources. A permit will be required to discharge sewage effluent to a soil absorption system, drainfield, or waterway.

UK Government Septic Regulations are found at

• Septic tanks and treatment plants: permits and general binding rules Environment Agency National Customer Contact Centre
  Web: gov.uk/permits-you-need-for-septic-tanks Email: enquiries@environment-agency.gov.uk Telephone: 03708 506 506 Monday to Friday, 8am to 6pm Find out about call charges Environment Agency Quadrant 2 99 Parkway Avenue Sheffield S9 4WF

Terminology note: Cesspool vs. holding tanks

In the U.S. a cesspool is an underground holding system that receives raw sewage and permits effluent to discharge into surrounding soils.

Cesspools do not treat effluent because of their depth in the ground (lacking exposure of effluent to sufficient aerobic bacteria) and because of the limited volume of soil available to perform any treatment.