The utilities superintendent, or such authorized representative as the utilities superintendent may designate, is authorized and directed to make adjustments or authorize such adjustments to be made, to any billing rendered by the utilities division for any charge for water service including, but not limited to, connection charges, minimum monthly billings, fixed rate and metered charges, penalty and special charges, adjustment of billings due to vacancies, improperly charged rates, and the cancellation of uncollectible bills and accounts, subject to rules and regulations as the city council may promulgate from time to time. Adjustments for leakage will be calculated such that the customer is charged for the average consumption for the leakage period determined from historical records for the same time period in previous years, plus one-half of the excess consumption under the base water charge plus the filtration charge on the total consumption. (Ord. 1237-86 § 82, 1986.)