The Hydro DryScreen® is a next-generation baffle box that captures sediment and screens trash and other solids, storing organic materials such as leaf litter dry to prevent nutrients from leaching into surface water between storm events. Improving on the conventional baffle box design with the inclusion of a patented flow diffusing mechanism, the system is designed to be resistant to blocking and blinding, and requires significantly less maintenance than other screening technologies.


  • Regions with larger pipes and high peak flows
  • Installations requiring low headloss, such as relatively flat drainage profiles
  • Shallow installations where high groundwater or bedrock present excavation challenges
  • Areas where trash and nutrients in stormwater is particularly problematic

Only Hydro DryScreen®

  • Has a patented flow diffuser that evenly spreads debris, improving performance and reducing the risk of blockage so you can go longer between servicings

Designed for

Coarse particles

High flow


Trash & floatables


Prevent nutrient pollution

Hydro DryScreen® stores leaves and organic material dry, rather than in a wet sump, preventing nutrients from leaching into stormwater. Other screening baffle box designs send flow directly from inlet to outlet without slowing down the flow, causing debris to collect in piles and quickly blind some areas while not using other areas; in these boxes the velocity of direct flows are more likely to tear apart organic matter where it will fall into the wet sump and become dissolved nitrogen and phosphorus. 

Improve sedimentation performance

When the flow path is redirected by the patented flow diffuser it increases the time during which total suspended solids (TSS) remain in the Hydro DryScreen®, encouraging sedimentation.

Reduce blinding

The flow diffuser distributes flow and debris evenly across the entire screen, reducing the risk of blinding.

Cut maintenance

The even flow distribution reduces the risk of ragging and blockage, and a larger screenings storage capacity than conventional baffle boxes mean that the Hydro DryScreen® requires significantly less maintenance.

Adapt to a variety of site conditions

The Hydro DryScreen® works well with high peak flows, large pipes, shallow sites or anywhere where low headloss must be accommodated. The elevation can be adjusted to account for tail water or base flows.

How it works

Baffle box sedimentation is a relatively simple pollutant removal process based on the principle of slowing the velocity of flow through a pipe in order to allow solids to settle out of the flow stream.

  1. As stormwater enters the Hydro DryScreen® chamber, the flow is diffused and slowed by the Flow Spreader.
  2. Gross solids are conveyed around the spreader and captured on the horizontal screen.
  3. As the flow encounters the first baffle wall, the velocity slows again allowing particles to settle.
  4. Other solids in the flow stream strike the baffle wall and settle to the sump where their further movement is impeded by the presence of the baffle.
  5. Flow continues through the next two baffle chambers, where smaller particles settle.


Technical information

          Hydro DryScreen Stormwater Technical Specifications