Constructing, purchasing, or extending waterworks; borrowing; expenditure.

Sec. 3. It shall be lawful for a city, subject to the provisions of this act, to borrow money to be used exclusively for the purpose of purchasing, constructing, or extending waterworks, as provided in sections 1 and 2 of this chapter. The total amount expended for constructing, purchasing, or extending such waterworks shall not exceed the estimate of expense provided for in section 4 of this chapter.