Soakaway's for rainwater, septic tank to soakaway for all sink and blackwater, this is commonplace in rural locations around here.
Septic tanks don't operate as well these days because cleaners and bleach kills the bacteria in the tank resulting in less biodegradation.
Ours worked well untill children came on the scene, increased toilet and washing machine use caused the soakaway to fail. We now have a recieving tank with a pump that goes to a herringbone pipework system on the Forrest floor.
