A. If a water meter is not functioning properly as determined by the department, or if a meter reading is not taken for a given month, the billing for that month shall be determined by averaging a customer’s last four reliable water meter readings within the appropriate six-month period (October through March or April through September), as determined by the department and the chief fiscal officer. The readings may be taken from a period as long as three years previous to the billing, as long as a customer occupied the same building at that time. If such reliable readings are not available, the billing may be based upon another customer’s average consumption for four appropriate months (as determined above); provided, that the other customer is reasonably comparable with respect to the number of people living in or using the establishment, numbers of washing machines, dishwashers, showers, water closets, or other facilities requiring a significant volume of water.

B. When weather or other conditions make it impractical to read water meters, monthly billings for metered customers shall be based upon an estimated consumption in accordance with the procedure set forth above. The next month in which the water meters are read, the billings shall be based upon the sum of the average monthly consumption for each month between the most recent and previous actual reading of the water meter, less the amount of estimated usage during the period the billings were based upon estimated usage.