Amends GS 160A-312 (concerning cities) and GS 153A-275 (concerning counties), which authorize cities and counties to operate public enterprises, and enacts GS 162A-900 (concerning water or sewer authorities and districts) and GS 130A-64.2 (concerning sanitary districts) to require that these entities bear the cost to comply with any adopted rule that applies to customers who have received previous approval to connect to the specified system. Specifies that the cost to comply with a numerical pretreatment standard for each of these specified systems will be borne by the customer. Applies to compliance costs arising on or after the act becomes law.