Septic tank
While a properly maintained and located septic tank does not pose any more environmental problems than centralized municipal sewage treatment, certain problems can arise with septic tanks in unsuitable locations. Since septic systems require large drainfields, they are not suitable for densely built 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.