Combined sewer system (CSS)
Combined sewer system (CSS) means a wastewater collection system owned by a State or municipality (as defined by section 502 of the CWA) which conveys sanitary wastewaters (domestic, commercial and industrial wastewaters) and storm water through a single-pipe system to a Publicly Owned Treatment Works (POTW) Treatment Plant (as defined at 403.3(r) of this chapter).