Collectively, all of the property involved in the operation of a sewer utility. It includes land, wastewater pipes, pumping stations, treatment plants, and general property. It may also be called a sewerage or wastewater system.
The drainage conveyance that takes wastewater from home plumbing systems (toilets, showers, sinks, washers, etc) and takes it to a sanitary sewer plant (Hyperion Treatment Plant for the greater LA area). More info here.
A system of interconnected, underground pipes and pumps that transport wastewater (used water) from homes, businesses, or industries to the centralized wastewater treatment plant. The sewer system and wastewater treatment plant can be either publicly or privately owned and operated, however, the former is more typical.