The utility shall bill each customer as promptly as possible following the reading of his meter. The bill shall show:

(1)           The reading of the meter at the beginning and at the end of the period for which the bill is rendered.

(2)           The date on which the meter was read at the end of the billing period.

(3)           The number of units metered.

(4)           Identification of the applicable rate schedule.

(5)           The gross and/or net amount of the bill.

(6)           The date by which the customer must pay the bill in order to benefit from any discount or to avoid any penalty.

(7)           A distinct marking to identify an estimated bill.

(8)           Any conversion from meter reading units to billing units, or any calculations to determine billing units from recording or other devices, or any other factors, such as purchased gas or fuel adjustments, used in determining the bill. In lieu of such information on the bill, a statement must be on the bill advising that such information can be obtained by contacting the utility's principal office.