Idaho Code § 30-802
Any corporation created under the provisions of this title for the purposes named in this chapter, subject to the reasonable rules and directions of the city or town authorities as to the mode or manner of using such right of way within the city or town, and subject to the reasonable rules and directions of the board of county commissioners as to the mode and manner of using any right of way outside the corporate limits of such city or town, may use so much of the streets, alleys and ways in any city or town, or the public roads and highways within the county, as may be necessary for the laying of pipes for conducting water to its consumers, or the building and maintaining of ditches, canals, pipes, flumes and aqueducts in conducting water from outside points to the corporate limits of said city or town.
Idaho Code § 30-802