Human excrements (feces and urine) as found in closets and privy vaults
are known as night soil. These wastes may be flushed away with running
water, and there may be added the discharges from washbasins, bathtubs,
kitchen and slop sinks, laundry trays, washing vats, and floor drains.
This refuse liquid product is sewage, and the underground pipe which
conveys it is a sewer. Since sewers carry foul matter they should be
water-tight, and this feature of their construction distinguishes them
from drains removing relatively pure surface or ground water. Sewerage
refers to a system of sewers, including the pipes, tanks, disposal works,
and appurtenances.