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General binding rules: small sewage discharge to the ground

New rules came into force on 1 January 2015. If your system was installed and discharging before 31 December 2014 you have an ‘existing discharge’. If your system was installed and discharging on or after 1 January 2015 you have a ‘new discharge’. Rules for both existing and new discharges are as follows;

  1. Use the correct treatment system - You must use a septic tank or a small sewage treatment plant to treat the sewage and then discharge the effluent to ground via a drainage field. NB. You cannot use a soakaway (designed for draining rainwater), well or borehole for discharging effluent to ground. Instead you must either upgrade to a drainage field or apply for a permit so that the Environment Agency can assess the risk of using this sort of system in your location.
  2. Your treatment plant must meet the right British Standard - the standards currently in force for new systems are; BS EN 12566 for septic tanks and small sewage treatment plants BS 6297:2007 for drainage fields.
  3. Your treatment plant must be installed correctly and have enough capacity
  4. Have your treatment system regularly emptied and maintained
  5. If you sell your property: tell the new owner about the sewage treatment system
  6. If you stop using your treatment system: make sure it’s properly decommissioned.

The rules are designed to reduce the level of pollution from sewage in the nation’s watercourses. Under the General Binding Rules which were updated in November 2019, anyone with a septic tank discharging into a watercourse must have plans in place to replace it or upgrade the foul water solution within a reasonable timescale, typically 12 months, or sooner if the property is due to be sold or if the Environment Agency finds it is causing pollution.

There are 5 options available to you;

1. Systems can be replaced by connecting to a mains sewer, if one is available. 2 You can install a drainage field (infiltration system) so that the septic tank discharges into the ground, if you have the available space to do so.

3 Systems can be replaced with a small sewage treatment plant.

4. In exceptional circumstances, a permit can be applied for to allow discharge to surface water.

5. You cannot use a septic tank conversion unit or a reedbed for discharging effluent to a watercourse under the general binding rules. Instead you must either upgrade to a package treatment plant or apply for a permit so that the Environment Agency can assess the risk of using this sort of system in your location. If you apply for a permit you will need to include supporting information to show that the treatment system will treat your sewage to an appropriate standard.

Follow this flow chart to establish what you should do in order to make sure your treatment system meets the general binding rules:

Binding rules sewage treatment changes

The Building Regulations 2000 - Drainage and Waste Disposal 2002 edition Part H-H2 Package Sewage treatment Works

The main provisions of these regulations are:

  • The Sewage Treatment Plant must be sited more than 7m from habitable property
  • The soakaway must be a minimum of 10 metres from a watercourse, 15 metres from a building and 50 metres from a borehole or spring.
  • The soakaway must be designed to BS6297: 2007 and all percolation test results must be submitted. 
  • The discharge point shall be more than 10m from habitable property
  • If the discharge is to a soak away a sampling chamber must be provided before the soak away. These are available from WTE Ltd..
  • Soakaway drains must be constructed in the aerobic soil layer, i.e. within 700mm. of ground level.