There are a number of small scale community-based alternatives to centralized wastewater treatment systems.  Septic systems are the most common technology employed in rural and low density residential areas .  Other options include constructed wetlands and lagoons, aquatic plant systems, mound systems and sand filters.  These have proved to be very effective practices for treating sanitary sewage under certain conditions. 

For a discussion of wastewater treatment techniques employed at large centralized wastewater treatment plants in Toronto, click here.