The treatment performance of community based (decentralized) wastewater treatment systems are not monitored by municipalities in Tanzania and therefore these systems pose pollution threat to receiving water bodies. The aim of this research is to assess and compare the treatment performance of existing community based technologies which are affordable, manageable and climate compatible in Tanzania. The selected existing decentralized technologies for this study were Anaerobic Baffled Reactor (ABR) found in Kigamboni, Dar es Salaam and Constructed Wetland (CW) found in Mbagala, Dar es Salaam. Wastewater samples in and out of these systems were collected and analyzed for physical, chemical and biological parameters. The observed average effluent concentration of BOD5 (67.5, 90 mg/L), NH3-N (276.6, 115.7 mg/L), PO4-P (13.2, 17.7 mg/L) and FC (9 x106, 4.2x106 counts/100mL) in ABR and CW, respectively testified to an inferior standard of treatment caused by mismanaged operation and maintenance. Both ABR and CW with slight adjustment were found to be effective in removal of all physical, chemical and biological parameters.