A Soakaway, or dry well, is a underground cavity or 'infiltration device' designed to dissipate excess water. They are common where direct connection to a public sewer would be impractical.
Unwanted water, such as stormwater runoff, is safely disposed of via the Soakaway by merging with the surrounding groundwater. Water enters the Soakaway though entry pipes, and is discharged through small holes around the sides and base of the structure.
The process occurs passively as a result of gravity, and by distributing the water over a wider surface area (the network of exit holes). The internal cavity of a Soakaway will contain mostly air, so that it can accept a large volume of water quickly, such as during heavy rainfall. This water can then be slowly disposed of over time.
Basic Soakaways often consist of a simple pit, which can be at risk of collapse.
These pits may be filled with gravel or other debris to resist collapse, but the capacity of such dry wells is considerably lower than more advanced Soakaways.
Modern Soakaways are generally prefabricated, and should not require much maintenance. Regardless of the age of the Soakaway, their effectiveness will lessen if silting or other contamination occurs.
When the Soakaway is empty, silt may be manually removed. However, if the cavity has collapsed or silted up entirely, the whole dry well may need to be excavated and rebuilt.