sew ‧ age /ˈsjuːɪdʒ, ˈsuː- $ ˈsuː-/ BrE AmE noun [uncountable]
[ Date: 1800-1900 ; Origin: sewer ]
the mixture of waste from the human body and used water, that is carried away from houses by pipes under the ground:
Chlorine is used in sewage treatment.
The factory secretly dumped millions of gallons of raw sewage (=sewage that had not been treated) into the Ohio river.