This article discusses the development of machine learning models for forecasting effluent SCOD of domestic wastewater after treatment using a two-stage anaerobic onsite sanitation system. The models were tested using data collected from a laboratory scale reactor and showed promising results. The system consisted of a modified septic tank and an anaerobic filter, and was able to effectively treat domestic wastewater. The study also looked at the effects of different operating conditions on the system’s efficiency.