The cost linked the economic or relative scarcity of water once it is used.

Ponds or pools with additional storage capacity to attenuate surface runoff during rainfall events.ﾠ Retention time of runoff can provide the capacity to remove pollutants through sedimentation and opportunity for biological uptake of nutrients.
- Based on Stella definitions, adapted by NWRM project experts and validated by the European Commission

Excavations, typically filled with gravel, designed to store water and allow it to infiltrate into underlying soils or aquifers.ﾠ Soakaways would typically receive point-source inflow (e.g. from roof drainage).ﾠﾠ
- Based on Stella definitions, adapted by NWRM project experts and validated by the European Commission