Sewer Absorption Trenches

What is a Sewer Absorption Trench?

Sewer Absorption Trenches, also known as absorption beds, are used to release effluent (liquid sewerage) underground through deep narrow trenches or wide shallow beds. The effluent generally flows through the trench by gravity but can occasionally require additional force, it is then filtered through gravel and absorbed by surrounding soil. Bacteria within the soil naturally treats the pollutants and pathogens in the effluent.

Sewer Absorption Trenches are most commonly used with septic tanks, but may also be used with composting toilets, biological filters, and aerated wastewater treatment systems.

How do I know if my Sewer Absorption Trench is damaged?

You will be able to tell if your Sewer Absorption Trench is damaged by the area around it becoming damp, pungent, and covered in dense grass. You may also notice that toilets take longer to flush, drains take longer to clear, odours are present outside the house, and gurgling noises are coming from the sewerage.

If you notice any of the signs above, please contact Fluid Services immediately to resolve the issue before serious damage can be sustained.

Why choose Fluid for your Sewer Absorption Trench construction?

If you’re building a new property that requires Sewer Absorption Trenches, or if your existing trenches require modification, give the experts at Fluid Services a call. Our technicians construct Sewer Absorption Trenches with the utmost efficiency and precision, so that your sewerage system stays out of sight and out of mind for as long as possible.


  • How deep should a Sewer Absorption Trench be?
    Generally these trenches will be between 500 and 700 millimetres deep. 
  • How does a Sewer Absorption Trench work?Gravity forces effluent through the absorption trench, where it is then filtered through gravel or sand to be absorbed by the underlying soil.
  • How long will a Sewer Absorption Trench last?
    If properly maintained, Sewer Absorption Trenches should last between 15 and 25 years.

Fluid Services is a Sydney Water accredited Sewer Mains Contractor that has the capabilities, qualifications and experience needed.

Call now on 1300 035 843