(A) All customers of the sewage works will be included in a user class and each user class will pay for its proportionate use of the sewage works in terms of volume and pollutant loading. Sewer user charges are levied to defray the cost of operation and maintenance (including replacement and depreciation).
(B) The classes of users of the sewage works, for the purpose of determining the user charges, shall be as follows.
(1) Class I - Residential shall include those customers which discharge only segregated domestic wastes or wastes from sanitary conveniences and are defined as “Residential Users” in § 51.002.
(2) Class II - Commercial shall include those customers which did charge only segregated domestic wastes or wastes from sanitary conveniences and are defined as “Commercial Users” in § 51.002.
(3) Class III - Institutional shall include those customers which discharge only segregated domestic wastes or wastes from sanitary conveniences and are defined as “Institutional Users” in § 51.002.
(4) Class IV - Governmental shall include those customers which discharge only segregated domestic wastes or wastes from sanitary conveniences and are defined as “Governmental Users” in § 51.002.
(5) Class V - Industrial shall include those customers which discharge industrial sewage and are defined as “Industrial Users” in § 51.002.