Products / Techniques

Hydrodynamic Vortex Separation

Water quality control is an inherent part of surface water and stormwater management, and Downstream Defender® is ideal for preventing pollutants from reaching watercourses.

Downstream Defender® hydrodynamically removes and retains sediments, floatables and hydrocarbons from storm flow.  Its space-saving technology can enhance SUDS schemes and provide protection for natural SUDS features.  It can also supplement the treatment train in storage and flow control projects.

With a smaller footprint and higher performance than conventional gravity or simple swirl-type devices, Downstream Defender® ensures solids/liquids separation with washout prevention over a wide flow range. The unique, flow-modifying design isolates and stores captured sediments and traps oil and floatables, preventing re-entrainment even under extreme surcharge conditions.


  • Wide flow range efficiency
  • No pollutant re-entrainment
  • Minimum flow disruption with low system headloss
  • Internal bypass with high flow capacity
  • Minimum maintenance, periodic sediment removal with standard gully vacuum tanker
  • Independently tested and verified performance, world-wide regulatory agency approval
  • Flexible drainage scheme compatibility, with adaptable inlet/outlet angle

View Best Practice Case Studies about Downstream Defender®

Learn more about Hydro’s Downstream Defender®