Small sewage discharges are regulated by two sets of rules, the General binding rules: discharges to ground and General binding rules: discharges to surface water (“the Rules”). These set out a series of conditions and technical requirements specified by the Environment Agency and designed to protect water resources from pollution.
The Rules set out the minimum standards that septic tanks and sewage treatment plants need to meet in order to be used without an environmental permit.
They do not apply to cesspits, which are completely enclosed and simply collect and store sewage.
- In England, you do not need to register your septic tank or obtain a permit (unless you are making a discharge in a designated area, see Additional Rules).
- By making a small sewage discharge without a permit, you are in effect agreeing to be bound by the Rules.
- Ignorance of the Rules is no defence to prosecution for breach of the Rules.
- The discharge must not cause pollution of surface water or groundwater. See British Water’s Guide for users of small wastewater treatment plants. Much of the guidance also applies to septic tanks.
- You can discharge up to 2 cubic metres (2000 litres) per day to the ground using either a septic tank or small sewage treatment plant. The Environment Agency has published a calculator for householders to work out their daily discharge: Sewage discharges calculator for domestic properties.
- You can discharge up to 5 cubic metres (5000 litres) per day to surface water (e.g. a river or stream) if you use a small sewage treatment plant instead of a septic tank.
- The sewage must receive treatment from a septic tank and infiltration system (also known as a drainage field) or from a small sewage treatment plant.
- The discharge must not be within a groundwater Source Protection Zone 1 (SPZ1) or within 50 metres from any well, spring or borehole that is used to supply water for domestic or food production purposes. This is to protect vulnerable or sensitive (usually drinking) water supplies.
- You will know where your own well or borehole is, if you have one. To check whether your neighbours have one, or whether you are within a protected zone, call the Environment Agency on 03708 506 506.
- For discharges in tidal waters, the discharge outlet must be below the mean spring low water mark.
- Your system must comply with the relevant design and manufacturing standards, i.e. the British Standard that was in force at the time of the installation, and any guidance issued on the capacity of the equipment. If the system was installed before 1983, there was no British Standard in place so you do not have to comply with this rule.
- The system must be installed and operated in accordance with the manufacturer’s specification.
- The works of installation must comply with the Building Regulations that were in force at the date of installation. Current regulations are in Approved Document H2.
- Maintenance must be undertaken by someone who is competent. A list of competent engineers is maintained on the British Water website British Water: Accredited Service Technician.
- Waste sludge must be safely disposed of by an authorised person before it exceeds the maximum capacity. As a minimum, your system should be desludged at least once a year or in line with the manufacturer’s instructions. ‘Authorised’ means having a waste carrier’s licence to transport controlled waste between its source and its legal place of disposal, usually the local municipal wastewater treatment plant.
- You must have your treatment system repaired or replaced if it is not in good working order, for example, if it has leaks, cracks in tank walls or pipes, blocked pipes, signs that the effluent is not draining properly (pools of water around the drainage point), sewage smells, or a failed motor, pump or electrical supply.
- When you sell your property, you must give the new owner a written notice stating that a small sewage discharge is being carried out, and giving a description of the waste water system and its maintenance requirements.
- The system must be properly decommissioned once it ceases to be in operation so that there is no risk of pollutants entering groundwater, inland fresh waters or coastal waters.
For discharges starting on or after 1 January 2015 (known as “new discharges”), there are additional requirements, as follows:
- You must have both planning permission and building regulations approval for the system. Local planning authorities have varying views about whether planning permission is required in their areas, so you should ask them for advice on this point.
- Discharges are not permitted if any part of the building that the system serves is located within 30 metres of a public sewer or if the discharge could reasonably be made to the foul sewer.
- New discharges must be made to a watercourse that normally has flow throughout the year.
- For any new discharges to surface water, any partial drainage field must be installed within 10 metres of the bank side of the watercourse.
- You may not discharge into an enclosed lake or pond.
- You will need a permit if the discharge is in or close to a designated sensitive area.
The rules are more stringent in Wales. If you live or own a property in Wales, you must register your septic tank or sewage treatment plant with Natural Resources (Wales) and will require a consent for any discharge to ground through a watercourse or drain field.
For more information, please go to Natural Resources Wales: small sewage discharges.
If you want more information or advice about off-mains drainage, please contact Sarah Keens or Deborah Caldwell.