Retention is a key feature of Water Sensitive Design (WSD).

Unlike traditional detention systems, which typically detain and discharge runoff from a single outlet pipe, retention systems allow stormwater runoff to be retained onsite and re-used for irrigation, water supply or percolated into the subsoils.

On sites where soils drain well and the water table is low enough, a stormwater infiltration system may be the most economical means for managing runoff.

Water quality is usually improved through the soil’s natural filtering ability, and infiltration systems can also minimise water table reductions.