Section 71.
The council shall have the power and is authorized to lay down all necessary sewers and drains and ditches, and cause the cost of the same to be paid out of the general fund of the city, or to be apportioned and assessed on all the property directly or indirectly benefited by such sewer, drain, or ditch, when the council shall direct the same to be assessed upon the property directly or indirectly benefited, such expense and cost shall be apportioned, assessed, and collected as in sections 50 to 68, inclusive of this act, provided in the case of "street improvement"; Provided, the council shall not necessarily be limited to the property immediately adjacent thereto or abutting thereon in such apportionment and assessment: Provided further, the council may, at its discretion, appoint three disinterested persons to estimate and determine the proportionate share of the cost of such sewer, drain or ditch, to be apportioned and assessed to the several owners of property benefited thereby. Such viewers, after their appointment by the council, shall perform their duties in the manner hereafter to be provided by ordinance by the city council.