Sewage Treatment Plant or Septic Tank: What is the difference?

Which one do I need?
When it comes to choosing which one you need it depends more on your circumstances i.e. site restrictions, permit requirements and cost. However you should always choose the option that is fully compliant with current laws surrounding sewage treatment, for example, regulations set out in 2020 mean septic tanks can no longer legally discharge directly into a river or stream, they must drain into the public sewer system or into a drainage field, which makes a Sewage treatment plant the more convenient option if possible to install.

A quick look as the what the difference is:

Septic tanks:

  • Separates solid and liquid waste
  • Doesn't need a power supply
  • Relatively low installation, running and maintenance cost
  • Less servicing required overall
  • Doesn't treat liquid waste
  • More regular emptying required
  • CANNOT be emptied directly into watercourses
  • Only suitable if the ground is porous enough for a soakaway system

Sewage treatment plants:

  • Separates solid and liquid waste
  • Treats liquid giving a higher quality effluent
  • Less regular emptying required
  • CAN be discharged directly into a watercourse (Check local regulations first)
  • Sewage treated to a higher standard so has less impact on the environment
  • The only non-mains solutions that enables direct discharge into a watercourse
  • Mechanical parts require connection to a power supply
  • Mechanical parts require regular maintenance 

When it comes to choosing which one to have there is a clear winner in terms of pro's vs con's. However as I previously said, most of the time the choice comes down to your situation, and whether you fall under the right categories for each type of tank.

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