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.
Cesspit
Most residential waste cesspools in use in the US today are rudimentary septic systems, consisting of a concrete-capped pit lined with concrete masonry units (cinder blocks) laid on their sides with perforated drain field piping (weeping tile) extending outward below the level of the intake connection. The concrete cover will often have a cleanout pipe extending above ground. Some are constructed with concrete walls on one or more sides.