Septic tank
In the United States, the 2007 American Housing Survey indicated that about 20 percent of all households rely on septic tanks, and that the overwhelming majority of systems are located in rural (50%) and suburban (47%) areas. Indianapolis is one example of a large city where many of the city's neighborhoods still rely on separate septic systems. In Europe, septic systems are generally limited to rural areas.
Acton, Massachusetts
Most homes and businesses in Acton (approximately 80%) use private on-site sewage systems (i.e. septic tanks). Higher density developments such as condominiums and apartment buildings (approximately 10% of the town) use private sewers which go to small-scale private treatment plants.