Minn. Stat. § 456.29: WATER MAINS BEYOND CITY.

A city of the first class that owns and operates a water plant or department, whether the water plant is under the control of the council or a board of water commissioners, may furnish water to a contiguous city or town. The furnishing city may extend its mains and assess the cost of extending them against the property abutting the street where the mains are laid.