Where there is a leak under the street, and it is doubtful whether the water comes from a break in the city main, or from a private service pipe, the water department will make an excavation to determine which it is from. If the leak is found to be from the main, the water department will make all repairs, free of charge; but if it is from the service pipe, the owner of the property or agent will be notified and must immediately take charge of the excavation, repair the leak, and replace the street, and be responsible for all damages which may result. In case the owner or agent does not make repairs at once, the water department will proceed, and all bills for labor and material will become a charge against said property and shall be collected from the owner or agent at the end of the month. In case the bill is not paid, the enforcement of payment thereof will be performed in the same manner as for the payment of bills for water rentals.