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.
Acton, London
Acton will host the starting point of the 25 kilometre Thames Tideway Tunnel (also known as the "Super Sewer") at the Acton Storm Tanks in Canham Road. This will be built to avoid the discharge of sewage from Combined Sewer Overflow into the River Thames.