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.
Tank Stream
From Hunter to Bond Street the Stream is a semi-circular stone arch with a shallow V shaped floor for 35 metres (1500 by 3000mm). The 1790 cut tanks were originally located in this area, but are not thought to have survived. For the following 86 metres, below Australia Square, the original sewer has been replaced with concrete box-profile pipe (1220 by 1830mm), inserted during the construction of the Square in 1962. The Australia Square Tower basement houses the access to Tank Stream for public tours and as an inspection point for Sydney Water.