The city council of all unclassified cities in this state are authorized to construct a sewer or system of sewers and to keep the same in repair; the cost of such sewer or sewers shall be paid from a special fund to be known as the "sewer fund" to be provided by the city council, which fund shall be created by a tax on all the property within the limits of such city: PROVIDED, That such tax shall not exceed one dollar and twenty-five cents per thousand dollars of the assessed value of all real and personal property within such city for any one year. Whenever it shall become necessary for the city to take or damage private property for the purpose of making or repairing sewers, and the city council cannot agree with the owner as to the price to be paid, the city council may direct proceedings to be taken by law for the condemnation of such property for such purpose.