sew·er·age /ˈsuərɪʤ, ˈsʊ(ə)rɪʤ/
  排水設備,汙水
  Sew·er·age n.
  1. The construction of a sewer or sewers.
  2. The system of sewers in a city, town, etc.; the general drainage of a city or town by means of sewers.
  3. The material collected in, and discharged by, sewers. [In this sense sewage is preferable and common.]
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  sewerage
       n 1: waste matter carried away in sewers or drains [syn: sewage]
       2: a waste pipe that carries away sewage or surface water [syn:
           sewer, cloaca]