The majority of UK homes and commercial premises – 95%, in fact – are connected to the main drainage system, so wastewater is drained and processed at a nearby wastewater treatment works.


For the 5% of homes and businesses not connected to the mains sewer system, there are a few key environmental factors to bear in mind when living with a septic tank or small sewage treatment plant.

Download the British Water Guide for Packaged wastewater treatment plants

Environmental tips for sewage treatment solutions

Follow these tips to make sure your wastewater system is kind to the environment.


  • Use cleaning products with little or no phosphate, as this can be harmful to the environment when it appears in the water discharged from your system
  • Avoid using bleach or caustic soda when cleaning your home or premises, as this can have a harmful effect on the microbes that process your wastewater
  • Keep your sewage system well-maintained, serviced and emptied to avoid harmful build-ups and discharges
  • Don’t pour solvents or oil down the drain or sink
  • Space out washing loads so your system doesn’t become overloaded
  • Never let rainwater drain into your wastewater system.


Remember, you’re responsible for the maintenance and repair of your sewage treatment system, so it’s vital to comply with Environment Agency standards and regulations to avoid penalties.


For more information about sewage regulations, visit www.gov.uk/small-sewage-rules

Environmental advice for sewage treatment system users

  • Septic tank discharge must flow into a drainage field, not surface water, for environmental reasons
  • Small sewage treatment plants can discharge directly into surface water, as the process removes some harmful nutrients from the effluent
  • Older septic tanks that still discharge effluent into surface water must be updated or replaced, or a dedicated drainage field must be created, to comply with Environment Agency regulations.


For permit advice, please see our blog  or call us on 01706 813733 for further information.


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