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Non-mains drainage

The NPPF (paragraphs 174 and 1831) stresses the need for LPAs to take into account the effects of pollution on health and the environment and to ensure that development is appropriate for its location. The Government’s planning advice on the use of non-mains foul drainage in England is contained within the Planning Practice Guidance (PPG) for Water supply, wastewater and water quality2 (PPG). The principles set out in the PPG are expanded upon in Building Regulations Approved Document H3.

The PPG paragraph 20 states that ‘applications for developments relying on anything other than connection to a public sewage treatment plant should be supported by sufficient information to understand the potential implications for the water environment’. 

When drawing up wastewater treatment proposals for any development, the first presumption is to provide a system of foul drainage discharging into a public sewer to be treated at a public sewage treatment works (those provided and operated by the water and sewerage companies). This will need to be done in consultation with the sewerage company of the area.

Any discharge from a wastewater treatment system is likely to require a permit from the Environment Agency. Note: Initial contact with the Environment Agency is normally made as part of the planning procedures for non-mains drainage. Where there have not previously been such discussions with the Environment Agency, those seeking Building Regulations approval for non-mains drainage should contact the area office of the Environment Agency in order to determine whether a permit to discharge is required and what parameters apply. This should be done before an application is made for Building Regulations approval as it may have a direct bearing on the type of system that may be installed. Specialist knowledge is advisable in the detailed design and installation of small sewage treatment works and guidance is given in BS EN 12566 for septic tanks and small sewage treatment plants4 and BS 6297:2007 for drainage fields5.

Any planning application which includes a non-mains system should include sufficient information for an assessment to be made of the risks of pollution to the water environment.  The completion of a Foul Drainage Assessment form (FDA)6  for example, is submitted with your planning application, this will help to identify:

  • any concerns that might lead to pollution or nuisance arising from a non-mains drainage system
  • a need for significant changes to a developer’s intended foul drainage arrangements
  • an application for an environmental permit being refused, or particularly stringent conditions imposed.

Major developments

The Environment Agency is a statutory consultee for non-main drainage on major developments as detailed in Development Management Procedure Order (DMPO) Schedule 47.

Non-major developments

it is the local planning authority's (LPA's) responsibility to ensure proposals for non-mains drainage for non-major development8 complies with the National Planning Policy Framework (NPPF) and Planning Practice Guidance (PPG). 

Planning and environmental permitting

All discharges to ground located within a Source Protection Zone (SPZ) 1 for a potable water supply require an environmental permit and will not fall under General Binding Rules (GBR).

Visit the Environment Agency on to check if your proposals meet the General Binding Rules9 or if you need an Environment Permit for your sewage discharge.

Where planning applications and permits both are required, it is recommended that parallel tracking10 is used.

It is important to note that the Environment Agency will refuse permit applications for sewage discharges where the risks cannot be mitigated. For example, for direct discharge of sewage to groundwater; no subsequent environmental permit can be granted by the Environment Agency as the direct discharge of sewage related pollutants to groundwater is illegal under English law.

In such cases, the Environment Agency will also object when consulted on the planning application.

Nutrient Neutral Areas

Read further information about Nutrient Neutrality and the planning system11 from the Local Government Association.


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The Planning Portal is delivered by PortalPlanQuest Limited which is a joint venture between TerraQuest Solutions Limited and the Department for Levelling Up, Housing and Communities (DLUHC). All content © 2024 Planning Portal.