Ill. Admin. Code tit. 77 § 895.10
"Plumbing System" means the water service, water supply and distribution pipes; fixtures and traps; soil, waste and vent pipes; and building drains; including their respective connections, devices and appurtenances.
"Private Water Supply" means a water supply which serves an owner-occupied single family residence or dwelling.
"Public Water Supply" means a system for the provision to the public of piped water for human consumption, if the system has at least 15 service connections or regularly serves an average of at least 25 individuals daily at least 60 days per year. The term Public Water System includes:
any collection, treatment, storage and distribution facilities under control of the operator of such system and used primarily in connection with such systems; and
any collection or pretreatment storage facilities not under such control which are used primarily in connection with such system.
"Semi-Private Water Supply" means a water supply which is not a public water supply, yet which serves a segment of the public other than an owner-occupied single family residence or dwelling.
"Sewage" means waste water derived principally from dwellings, business or office buildings, institutions, food service establishments, and similar facilities.
Ill. Admin. Code tit. 77, § 895.10
Amended at 15 Ill. Reg. 18003, effective January 1, 1992