To determine the volume necessary for a rainwater or stormwater soakaway, a BRE Digest 365 test is performed. County Councils in Ireland now demand that a BRE Digest 365 test be conducted and submitted along with your planning application. Stormwater runoff must be captured immediately and allowed to efficiently infiltrate into the surrounding soil using soakaways.

It must quickly release the water that has been stored in order to have the capacity to handle runoff from a subsequent storm.

The size, shape, and infiltration properties of the surrounding soil all affect how long it takes for a discharge. They can be built in a wide variety of shapes and with a variety of materials.