In the schools of the Republic of Panama that are located in rural areas and sites that do not have municipal sewerage systems at present, many of the tender documents and project contractors refer to the Septic Tank system as the primary treatment system more versatile in terms of wastewater management and more economical in terms of construction and maintenance. This article make a comparative modeling between Septic Tank system and a UASB reactor to build wastewater treatment system in schools, highlighting the effectiveness for anaerobic treatment (Lozada, 2012), (Salazar-Larrota, Luis, et al, 2009) (Lorenzo y Obaya, 2006), furthermore of the economic viability in terms of cost to build and maintenance to take the option to improve wastewater treatment system with UASB reactor in tropical environments (Conil, 2001).