Definify.com

Webster 1913 Edition

Noun.

The construction of a sewer or sewers.

The system of sewers in a city, town, etc.; the general drainage of a city or town by means of sewers.

The material collected in, and discharged by, sewers.

[In this sense

sewage

is preferable and common.]

sewerage ‎(countable and uncountable, plural sewerages)

A sewer system.
Misspelling of sewage.
- 2010, India Today 5 Apr 17
  About 3.6 billion tonnes of untreated sewerage flows daily into the Yamuna, which supplies over 60 percent of Delhi's water.

sewer system

sewage — see sewage