Concrete CDS

The most efficient and compact hydrodynamic separator for storm sewers

The concrete CDS continuous deflection hydrodynamic separator is exceptionally efficient. It effectively controls and treats over 60%* of suspended solids, oils and floating debris from runoff water before discharge to an outlet.

New! Our CDS is also offered in HDPE. Discover now!

Model shown: CDS-5 with two inlets
* See current local regulations.


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Concrete CDS

Technical Documents


Advantages and Benefits

  • Designed for specific treatment rates, CDS provides customized solutions for each project.
  • For the same flow rate, CDS is the most compact option on the market, in diameter and height.
  • It saves money by reducing the footprint, unit size and excavation requirements.
  • It effectively removes 100% of floating and neutrally buoyant debris over 2.4 mm in diameter and recovers oil.
  • It provides a large storage capacity for oil, debris and sediment, reducing the frequency of maintenance.


  • New treatment installation;
  • Redesign or modernization of an existing structure into a treatment structure;
  • Replacement of traditional treatment system;
  • Pre-treatment for infiltration and bioretention;
  • Retention of sediment and debris upstream of watercourses;
  • Pump protection.

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A High-performance Product

That exceeds environmental requirements

Canada’s Environmental Technology Verification (ETV) program provides independent assessment of new technologies by providing assurance to sewer system owners and managers that environmental performance claims are valid, credible and supported by test data. This program provides a clear assessment of the environmental potential and value of the submitted technology.

The performance of the CDS hydrodynamic separator has been verified by the ETV Canada program and approved by Quebec’s MELCC.

Proven and Approved

  • The best performing hydrodynamic storm water treatment system, based on MELCC evaluation criteria.
  • CDS is also approved by the Washington State Department of Ecology (GULD* certification level) and the New Jersey Department of Environmental Protection (NJDEP).
  • Tested in various environments; in the laboratory and at dierent sites, this system has proven itself for over 20 years.
* General Use Level Designation



  1. Runoff and storm water enter the CDS through the main sewer lines or through the CDS surface grate.
  2. Sediments, floating debris and oils are directed to the central separation cylinder.
  3. The vortex created by the movement of the water forces the sediment to move towards the storage sump, where it will be retained.
  4. Floating debris are held in the centre of the separation screen; its unique design redirects debris to the centre of the vortex, preventing long-term clogging. The oils are retained by the oil baffle.
  5. Water that is now free of sediment, oil and debris is discharged under the oil baffle and redirected to the outlet.

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CDS is also offered in HDPE

Same technology, same performance now offered in a single-piece structure 50% lighter than the heaviest component of a Concrete CDS.

Discover our HDPE CDS