All meters of the city water system are the property of the city, and any regular maintenance to said meters shall be made by the city. If a meter is damaged by hot water or by the carelessness or negligence of the owner or occupant of the premises, the city water department will repair the meter, and the cost of such repairs shall be charged to the user. When a meter fails to register accurately, the charge for water used shall be either based on the average quantity of water used in a comparable period as shown by the meter when in order, or if there is no such average consumption, then the minimum rate of the city shall apply. If conditions make reading of the meters impracticable, an estimated reading shall be made by the city during the time such conditions exist. Estimated readings under other conditions affecting reading of a meter shall be made only on approval of the public works superintendent.