A soakaway is a pit that has good drainage properties. The soil in which the soakaway is built should have good drainage properties. A drainage pipe leads to the soakaway so that water from the surface of other areas is lead to the soakaway. To enhance the drainage properties the soakaway is filled with coarse stone and rubbles. Before constructing a soakaway it is better to consult the local authorities for the regulations governing the construction of the soakaway. In most of the places they recommend the soakaway to be 5 metres away from the building.
The minimum pipe size that flows to the soakaway should be 75mm in diameter and the preferred size is 100mm. The size of the soakaway should be 1m x 1m x 1m. This pit should be below the incoming drain pipe. Above 100mm of the pipe there should be a stone fill and this can be covered by an impervious layer of tarpaulin or thick polythene. On top of this you can have the soil at the garden level.