sewerage vs sewer

sewerage and sewer both are nouns.

Word	Noun	Adjective	Verb	Adverb
sewerage	Yes	No	No	No
sewer	Yes	No	No	No

As nouns, sewerage and sewer are synonyms defined as:

sewerage and sewer: a waste pipe that carries away sewage or surface water

Other synonyms of sewerage include cloaca.

sewerage (noun)	sewer (noun)
a waste pipe that carries away sewage or surface water	a waste pipe that carries away sewage or surface water
waste matter carried away in sewers or drains	misfortune resulting in lost effort or money
	someone who sews