HydroLatch (Flood Gates)

The Challenge

Flood protection is also necessary underground so that flood water does not come  through the “back door , i.e. through the sewer, to flood streets and houses. Streams and rivers overflow their banks more often, more intensively and above all, faster in these days. The warning and reaction times are shorter. Sand bag barriers and manually operated valves are time and work intensive.

The Way

All overflow sills, inlets and outlet sewers in combined and stormwater networks can be secured with HydroLatch® flood gates to prevent flooding of the sewer network. The flood gates work automatically and without electricity. The HydroLatch® flood gates also allow a safe overflow from combined and stormwater networks during rain. Even if the HydroLatch® flood gates are flooded, drainage occurs as long as the water pressure in the sewer network is higher. The special GNA CSO seal is reliable and durable. All HydroLatch® flood gates are project-designed so that the gate cover is light (low resistance = large flow-rate) but heavy enough to prevent lifting by flow velocity.

Ask us, we won’t leave you out in the rain.

The Products

The top-hinged HydroLatch® flood gates Model HLA-HK can be applied wherever there is sufficient height difference. They are designed as rectangular or round flood gates. They are installed in protected overflows and designed with more smooth-running covers than those positioned in the flow of water. This is achieved by extra weights or the angle of inclination.

Bottom-hinged  HydroLatch® flood gates Model HLA-FK can be applied wherever the water level difference is very small. The flood gates designed as floatable fish-belly gates. They can be adjusted exactly to the floating up point by filling counter weight water inside. The fish-belly gates have the advantage of low losses and are installed protected in overflow chambers.


  • Robust, stainless steel
  • No electricity
  • High operational reliability
  • Easy and fast to install
  • With fixing materials, frames, sealing and cover
  • Durable, reliable flood gate sealing
  • Opens on with smallest water pressure
  • Angle of inclination optional
  • Weights optional
  • Warning system optional
  • Engineering support from GNA CSO

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