Factors affecting the performance of septic tank systems treating domestic wastewater in developing countries

Septic tank systems are in widespread use for treating domestic wastewaters. They are particularly attractive to developing countries because they are simple in concept and, if correctly designed, installed and maintained, require little attention from householders. However, present design guidelines disregard the influence of climatic conditions and surface vegetation on septic tank system performance. A combined field monitoring and numerical modelling study was undertaken to evaluate how these factors affect the hydrological performance of septic tank absorption trenches. The study revealed that a substantial proportion of water inflows to trenches is lost via evaporation and transpiration.