Downstream Defender®

The Downstream Defender® separator is an advanced hydrodynamic vortex separator. Manufactured by Hydro International Ltd, it is available from Rocla under exclusive license in Australia.

Rotary and shear forces are generated to augment gravitational forces and remove settleable solids using a much smaller area than sedimentation basins. An oil and floatables trap within the vessel provides a compact solution for non point source pollution.

Testing at Coventry University (UK) has indicated that the Downstream Defender® separator can remove 68% to 99% of settleable solids, including large proportions of fine particles (less than 100 microns), 80% to 97% of free oils and floating gross pollutants.

Installing a Downstream Defender® separator is as simple as installing a standard access chamber. The Downstream Defender® separator is delivered to site completely fabricated, ready to be installed in the excavated hole and connected to the drainage system.


  • New developments
  • Car parks
  • Streets and roadways
  • Industrial sites
  • Construction sites
  • Shopping centres
  • Agricultural run-off
  • Mmine sites
  • Service stations
  • Wetland protection