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.
Miami Circle
In attempting to refute this claim, Ricicek pointed to two things. Firstly there was clearly a terracotta outflow from the tank that would not tie with the need for a sink, and the plans for the apartment complex clearly show a sewage outflow to the south, into the river. Secondly, returning to the analysis of the calcite buildup on the holes by the Florida Geological Survey, the bedrock that had been cut out to lay the tank had little or no duricrust, showing the considerable age difference between the septic tank construction and the Circle.