French Drains have been banned for sewage run-off in South Africa for all intents and purposes. If you use them and there is a system failure then you could be subject to massive fines

Due to ignorance, laziness or just plain old stubbornness, the number of failed french drains, which are by far the most used system for septic run off in South Africa, have caused massive pollution and destruction to underground water resources in the last 30 years . The Water Research Council has been researching this contentious issue since 1995 in conjunction with the CSIR and have published a number of documents in this regard.