(1)    A town, town sanitary district, village or city owning water, light or power plant or equipment may serve persons or places outside its corporate limits, including adjoining municipalities not owning or operating a similar utility, and may interconnect with another municipality, whether contiguous or not, and for these purposes may use equipment owned by the other municipality.

   (2)   Plant or equipment, except water plant or equipment or interconnection property in any municipality interconnected, situated in another municipality is taxable in the other municipality under s. 76.28.

   (3)   

      (a)    Notwithstanding s. 196.58 (5), a city, village or town may by ordinance fix the limits of utility service in unincorporated areas. The ordinance shall delineate the area within which service will be provided and the municipal utility has no obligation to serve beyond the delineated area. The delineated area may be enlarged by a subsequent ordinance. No ordinance under this paragraph is effective to limit any obligation to serve that existed at the time that the ordinance was adopted.

      (b)    Notwithstanding s. 196.58 (5), a municipality that operates a utility that provides water service may enter into an agreement with a city or village to provide water service to all or a part of that city or village. The agreement shall delineate the area within which service will be provided and the municipal water utility shall have no obligation to serve beyond the area so delineated. The agreement is not effective to limit any obligation to serve which may have existed at the time the agreement was entered into.

   (4)   An agreement by a city, village or town to furnish utility service outside its corporate limits to unincorporated property used for public, educational, industrial or eleemosynary purposes fixes the nature and geographical limits of that utility service unless altered by a change in the agreement, notwithstanding s. 196.58 (5). A change in use or ownership of property included under that agreement does not alter terms and limitations of that agreement.

   (5)   An agreement under sub. (4) under which a city or village agrees to furnish sewerage service to a prison, which is located in an area that has been incorporated since that agreement was made, may be amended to provide that the city or village will also furnish water service to the prison. An agreement amended under this subsection fixes the nature and geographical limits of the water and sewer service unless altered by a change in the agreement, notwithstanding s. 196.58 (5). A change in use or ownership of property included under an agreement amended under this subsection does not alter the terms and limitations of that agreement.

   (5m)   

      (a)    In this subsection:

         1.    “Municipality” means a city, village, or town.

         2.    “Public utility” has the meaning given in s. 196.01 (5).

      (b)    Notwithstanding subs. (3) and (4), a municipality in a county bordered by Lake Michigan and the state of Illinois may request the extension of water or sewer service from another municipality in that county that owns and operates a water or sewer utility if the request for service is for an area that, on the date of the request, does not receive water or sewer service from any public utility or municipality and the municipality requesting the service contains an area that, on the date of the request, receives water or sewer service from the water or sewer utility owned and operated by the other municipality. The municipality requesting the service extension may specify the point on the water or sewer utility’s system from which service is to be extended to the area that is the subject of the request. The municipality that owns and operates the water or sewer utility shall approve or disapprove the request in writing within 45 days of the date on which the request was made. The municipality that owns and operates the water or sewer utility may disapprove the request only if the utility does not have sufficient capacity to serve the area that is the subject of the request or if the request would have a significant adverse effect on the utility. A municipality making a request under this paragraph may appeal to the public service commission any decision of the municipality that owns and operates the water or sewer utility to deny the service extension. The public service commission may include in its decision conditions on the extension of service to ensure that costs resulting from the extension are borne by the users causing the cost and that the connection point selected by the municipality requesting the service is reasonable. Either municipality may appeal the decision of the public service commission.

      (c)    Paragraph (b) applies even if the municipality that owns and operates the water or sewer utility has, before July 14, 2015, enacted an ordinance or entered into an agreement specifying that the municipality is not obligated to provide utility service beyond an area covered by the ordinance or agreement.

   (6)   A town, village or city owning a public utility, or the board of any municipal public utility appointed under s. 66.0805, may enter into agreements with any other towns, villages or cities owning public utilities, or any other boards of municipal public utilities, for mutual aid in the event of an emergency or disaster in any of their respective service areas. The agreements may include provisions for the movement of employees and equipment in and between the service areas of the participating municipalities for the purpose of rendering aid and for the reimbursement of a municipality rendering aid by the municipality receiving the aid.