Stormwater management

During storm events, many wastewater plants may be unable to achieve the required effluent quality and in worst cases, untreated wastewater may bypass the plant. Combined sewer overflow (CSO) may contain particulate and soluble wastes from domestic sewage, industrial and commercial wastewaters. These waste products include suspended solids, bacteria, viruses, nutrients, toxic pollutants, oil, grease and debris, posing significant risks to receiving water quality, public health and aquatic life.


Veolia technologies to manage and eliminate combined sewer overflows

Veolia Water Technologies provides municipalities and industries with solutions to control and limit sewage overflows which are toxic for the environment. The Hydrovex® range of technologies addresses the needs of our clients whatever the characteristics of their installation may be. 

HYDROVEX® line of wet weather technologies

  • Flow control for stormwater runoff
  • Flow control for combined and sanitary flows 
  • Level control in collection systems
  • Floatables screening
  • Off-line or in-line retention and treatment

Hydrovex® includes several product ranges to help our clients carry out their activities:

  • Flow control is guaranteed by a wide range of solutions:
       - without energy and moving parts
       - without energy, with moving parts
       - powered flow control

Our equipment can include check valves, membrane regulators, and can measure flows to better regulate them.

  • CSO storage & treatment, using efficient technologies
       - Vortex separator
       - Self-regulated outlet slit
       - Sediment flusher
  • Overflow control allows the discharge of excess water in a dedicated location, ensuring a proportional flow progression as the head increases. These weirs are available with different 
  • Screens are used to filter solids present in stormwater, preventing debris from reaching weirs. Available at a low cost, they can limit the passage of solids of various sizes, down to 2 mm. 

HYDROVEX® VHV Vertical Vortex Flow Regulator

Veolia Water Technologies offers many regulation tools to safeguard against stormwater management and CSO risks. Among them, the VHV Vertical Vortex Flow Regulator combines hydraulic and electronic technologies to ensure a reliable and precise flow. The device works on any type of combined sewer system or network  and allows for real-time remote control. 

The Actiflo-storms settling process

Actiflo® is a process developed by Veolia Water Technologies particularly suited to the need for a high rate of clarified water. Actiflo®'s performance in treating stormwater discharges has been proven on numerous facilities around the world.

This water treatment technique: 

  • Removes solid residues suspended in water
  • Destroys oxygen-demanding particles
  • Guarantees high performance results

The Actiflo® process removes more than 90% of suspended matter. This:

  • reduces the need for particulate oxygen for biochemistry processes
  • enables water disinfection by chlorination or UV processes


Actiflo® can also be used in conventional water treatment plants as well as satellite collection systems. This offers:

  • Almost unlimited processing capacity
  • Protection against wastewater discharges during heavy rains

Finally, Actiflo® finds applications in primary and tertiary water treatment processes.

The superior performance of Actiflo® processes in treating stormwater discharges has been proven in installations around the world

Veolia Water Technologies, the water treatment specialists, protects municipalities and industries against the risk of storm water pollution. Our solutions are adapted to all wastewater basins, enabling treatment plants to reach their optimal potential by guaranteeing the quality of effluents, even during heavy rainfall.