(A) Sewer charges provided for in this chapter are based upon water purchased from the water system of the City.
(B) Said charges may be reduced when a portion of the water purchased is not discharged into the sanitary sewer system of the City and the amount thereof is measurable as follows:
(1) Based upon a water flow meter located in a sanitary sewer line;
(2) When a portion of the water purchased by a sewer user is not discharged into the sanitary sewer system and the amount of said water can be accurately metered;
(3) When water purchased by a sewer user is used in a manufacturing process and the amount thereof is subject to accurate measurement based upon metering or upon such records as are approved by the Public Works Superintendent and are kept by the sewer user in the ordinary and usual course of business; and
(4) When the water has leaked onto the ground or other surface and has not entered the sewer system. Credit for water not discharged to the sanitary sewer system shall be computed based upon water flow records prior to and after the leak has been fixed.