Infiltration Trenches

What are they?

  • Shallow trenches filled with rubble or stone to create subsurface runoff storage

Where can they be used?

  • Best used when run along an impermeable surface and receive inflow along the length of the trench
  • Ideal locations include playing fields, other public open space, roadways and parking lots

Who commonly uses them?

  • Residential
  • Industrial
  • High Density Areas
  • Retrofits

How do they work?

  • Create subsurface runoff storage
  • Water exfiltrates into surrounding soil from bottom and sides of the trench
  • Cleans water through physical filtration, adsorption, and biochemical reactions in the soil


  • Enhances natural capacity of ground to store and filter water
  • Reduces runoff rates and volumes
  • Reduces volume of runoff pollutants
  • Fits well beside roads
  • Easy integration
  • Low maintenance


  • High potential for clogging without pre-treatment, since they don’t trap sediments

Other Information

  • Volume of water depends on the infiltration potential of the soil underneath the trench
  • Quality of water treatment depends on the size of the fill material and pre-treatment
  • Need to be regularly inspected for signs of clogging
  • Need to perform removal and cleaning or replacement of stone