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.
Davyhulme Sewage Works
Conversion of the treatment process from chemical precipitation to septic tanks and sedimentation tanks began in December 1900, and was completed on 4 August 1904. The tanks covered an area of . Air was excluded from them by the formation of a scum on the surface, and anaerobic microbes broke down the sewage. The 'first contact bacteria beds' covered , with a similar area used for 'second contact bacteria beds'. There were also which were used for 'storm water filters'. The bacteria beds were filled with a media of coke or granite chippings, around which microbes formed a slimy film. The oxygen-loving microbes digested the organic matter in the sewage as it passed through the media.