Michigan Compiled Laws, Chapter 339. Occupational Code § 339.6101

(a) “Apprentice plumber” means an individual who is registered under this article as an apprentice.

(b) “Board” means the state plumbing board described in section 1105.  1

(c) “Building sewer” means that part of the drainage system that extends from the end of the building drain and conveys its discharge to a public sewer, private sewer, individual sewage disposal system, or other point of disposal.

(d) “Domestic water treatment and filtering equipment” means residential water treatment and filtering equipment used in 1-family and 2-family dwellings.

(e) “Journey plumber” means an individual, other than a plumbing contractor or master plumber, who is qualified to engage in the practical installation of plumbing and who is licensed as a journey plumber.