Exfiltration: Performance

Ability of exfiltration systems to meet SWM objectives

Water balance benefit	Water quality improvement	Erosion control benefit
Yes	Yes	Partial: depending on soil infiltration rate

The downward movement of water through the soil, the downward flow of runoff from the bottom of an infiltration BMP into the soil.

Loss of water from a drainage system as a result of percolation or absorption into the surrounding medium (e.g., the infiltration of water into the native soil through a perforated pipe wall as it is conveyed).

Stormwater Management

The accounting of inflow and outflow of water in a system according to the components of the hydrologic cycle.

Includes the protection of soil from dislocation by water, wind or other agents.

The rate at which stormwater percolates into the subsoil measured in inches per hour.