How Do Septic Tanks Work?

Diagram Showing How a Septic Tank Works

Septic Tanks are designed to collect sewage and wastewater from households that are not connected to the mains sewer.

The tank itself comprises of two chambers and, as wastewater and sewage enters the tank, solids are encouraged to settle at the bottom and begin to decompose in the lower chamber. Meanwhile, liquors flow through to a second chamber to allow any smaller suspended solids to settle before exiting the tank through the soakaway system and into the environment, subject to consent to discharge issued by the Environment Agency.

Septic Tanks are designed to be easy to use and trouble–free, but CSG has tips for Septic Tank owners, including:

  • Use of biologically friendly household cleaning products
  • Have the tank de-sludged regularly, ideally every six months
  • Don’t let commercial chemicals, medicines or hygiene products to enter the system
  • Don’t use large quantities of biological cleaning products or bleach
  • Bacteria in the tank is vital to the biological process


CSG has been supporting households with Septic Tanks for over 80 years and carrying out annual health checks to keep systems in perfect working order.

We offer a fast, friendly and efficient service for customers who depend on our Septic Tank emptying service, help with a blocked system or simply need advice from the experts in domestic sewage collection. Our operatives are all highly experienced and we’re also fully licensed by the Environment Agency to give you complete peace of mind.

For further information or to talk to us about your Septic Tank requirements with no obligation, please phone 0800 011 6600 or contact us.