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, Massachusetts
Most homes and businesses in Acton (approximately 80%) use private on-site sewage systems (i.e. septic tanks). Higher density developments such as condominiums and apartment buildings (approximately 10% of the town) use private sewers which go to small-scale private treatment plants.