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.
Abbey Mills Pumping Station
Lee Tunnel is a sewage tunnel that travels from Abbey Mills to Beckton Sewage Works and is designed to handle the 16 million tons of overflow sewage that was previously discharged into the River Lea each year. The tunnel boring machine's name, 'Busy Lizzie', was chosen via a competition open to local school children. Thames Water began construction in 2012 and on 28 January 2016, in a visit to the operations, London mayor Boris Johnson opened the tunnel for service.