Soak away

Here are a few regulations and useful tips relating to soak aways.

• For obvious reasons, the pit should be in a spot lower than the area being drained.
• A soak away should also be sited so that it will not saturate the foundations of any structure.
• The soak away needs to be permanently above the water table for effective filtration. If this is not the case, the excess water has nowhere to permeate.
• If using a pipe to carry the water to the soak away, it should be no less than 75mm (3in) in diameter, although a diameter of 100mm (4in) is the ideal size.
• A soak away should not be too close to other infiltration devices, otherwise the capacity of those devices, and the ground itself, will be impaired.
• It is also a good idea to position the soak away so that there is no risk of contamination from pollutants.

• Start by digging a pit approximately 1.2m x 1.2m x 1.2m (4ft x 4ft x 4ft). If you hit a layer of clay before reaching the required depth, simply make the soak away longer to make up for the lack of depth.
• Break up the earth at the base of the pit with a garden fork.
• Fill the hole up to about 100mm (4in) of the top with rubble. Use coarser rubble at the bottom and smaller stones at the top.
• The rubble pit then needs to be covered with a sheet of durable polythene.
• Then cover to polythene with a 75mm (3in) thick layer of general mix concrete: 1 cement with 2 sharp sand or 1 cement with 3 coarse aggregate.
• When the concrete has gone off the top of the soak away can be covered with either turf or soil to conceal.