An anaerobic digestion pilot system was implemented in June 2010 in the Moroccan village of Dayet Ifrah. The input material consists of toilet wastewater and cattle manure. Biogas is produced under anaerobic conditions. It is used for heating and cooking. This biogas system could be an useful sanitation technology due to its ability to treat wastewater. The biogas system was monitored over 86 days in summer 2012 to measure gas production. The average gas production recorded was about 1,870 l per day. This amount is sufficient for a farming family composed of 17 people. Our work seeks to find the most appropriate formula to predict biogas production under Moroccan conditions. We compared and ranked different formulas by applying principal component analysis and the ELECTRE III method. The variables studied were the chemical oxygen demand reduction and biogas volume measurements. The results show that the formula of Vedrenne is the most appropriate equation to predict biogas production in Moroccan rural areas (see Vedrenne (2007) ‘Study of Anaerobic Degradation Processes and Methane Production During Storage of Manure’. Environmental Science Thesis. ENSA, Rennes).