sewer        
noun [ C ] uk/sʊər/ us/ˈsuː.ɚ/
 下水道;排污管;阴沟
a large pipe, usually underground, that is used for carrying waste water and human waste away from buildings to a place where they can be safely got rid of
  a sewer pipe 污水管 
 A complicated system of sewers runs under the city. 城市的地下布有复杂的排污系统。 
 open sewer 明沟
a channel for carrying away waste water and waste from the human body that is above the ground and is not covered