If the utility distributes all or a part of its water through an agent but the sales are made to customers under rate schedules filed by the utility, the utility shall credit its revenue accounts with the full amount of sales to customers. The commission paid to the agent shall be charged to account 1800, Other General Expenses, and any distribution expenses charged by the agent shall be debited to the appropriate expense accounts. Agents shall credit the amount of commissions earned to operating revenue account 1615.2, Miscellaneous Water Revenues.