A Soakaway is a hole in the ground, traditionally, filled with rubble, stones or bricks. The idea is that the voids between the rubble create a storage space for the liquid, which then soaks away during dry periods. More recently, crates have been developed, as they provid a larger void volume, but they are illegal for sewage effluent and are for rainwater only
Although they are now illegal for sewage effluent, it is amazing how many 'Cowboy' installers still install them.
The reasons that soakaways are not allowed are these:
- It does not rain every day. Soakaway pits fill up when it rains and drain when it is not raining, but sewage effluent discharges EVERY day, with no dry days to allow the pit to drain. The pit becomes full and the sewage either 'backs-up' the pipes or bursts through the surface of the ground.
It is not a serious matter if rainwater bubbles to the surface of the ‘pit’ during extreme weather, but sewage effluent surface contamination is an entirely different scenario. Please visit Sewage Problems if you have soakaway issues with your current system. Also visit Failed soakaway drainfield insurance claims.
- The Building Regulations (and the BS 6297 2007) state that the sewage effluent MUST be in constant contact with the AEROBIC particles of the soil. As the aerobic soil layer ends at 1 metre below ground, soakaway pits are not allowed.
This is because sewage effluent, even from a sewage treatment plant, still contains bacteria and viruses. These must be digested by the aerobic natural soil bacteria, which cannot live lower than 1 metre below ground, as there is no air there.