seweryoudaoicibaDictYouDict[sewer 词源字典]
sewer: [15] Etymologically, sewer denotes the ‘removal of water’. The word comes via Anglo- Norman sever from Vulgar Latin *exaquāria, a derivative of *exaquāre ‘remove water, drain’. This was a compound verb formed from Latin ex- ‘out’ and aqua ‘water’. The derivatives sewage [19] and sewerage [19] are both native English formations.
=> aquatic[sewer etymology, sewer origin, 英语词源]
sewer (n.1)youdaoicibaDictYouDict
c. 1400, "conduit," from Anglo-French sewere, Old North French sewiere "sluice from a pond" (13c.), literally "something that makes water flow," from shortened form of Gallo-Roman *exaquaria (source of Middle French esseveur), from Latin ex- "out" (see ex-) + aquaria, fem. of aquarius "pertaining to water," from aqua "water" (see aqua-).

Specifically of underground channels for wastewater from c. 1600; figurative use of this is from 1640s.
sewer (n.2)youdaoicibaDictYouDict
"one who sews," late 14c., agent noun from sew (v.).