Mich. Comp. Laws § 325.1005a

Sec. 5a. (1) A supplier of water for a community supply shall not use customer site piping as a means to convey water to other portions of the supplier's system. (2) A supplier of water for a community supply shall not provide water service to customer site piping if an impact on the water quality of the public water supply has occurred or could reasonably be expected to occur as a result of the service. A supplier of water may discontinue water service to customer site piping as the supplier of water or the department considers necessary to protect the health of the public water supply customers.