A county shall: enforce the State Plumbing Code; or adopt and enforce a local plumbing code that meets or exceeds the minimum standards of the State Plumbing Code for the proper design, acceptable installation, and adequate maintenance of plumbing systems. In this subsection: “greywater” means used, untreated water generated by: a clothes washing machine; a shower; or a bathtub; and “greywater” does not include water from: a toilet; a kitchen sink; or a dishwashing machine. A county may not adopt or enforce a provision of a local plumbing code that prohibits a system that recycles greywater, as authorized under the State Plumbing Code. Unless the Board determines that a county is adequately enforcing the State Plumbing Code or a local plumbing code that meets or exceeds the minimum standards of the State Plumbing Code, the Board shall enforce the State Plumbing Code in that county. The Board may make a cooperative agreement with a county for the county to enforce: the State Plumbing Code; or if the county has adopted a local plumbing code, that code.