All money received by a municipality for the service of any utility owned and operated by the municipality, and all money, receipts, and returns received from any investments of the earnings of such utilities, shall be paid into the treasury of the municipality and kept in a fund known as the municipal utilities fund. All of the moneys, earnings, and receipts deposited in such fund shall be kept separate and distinct from all other funds of the municipality until used. The fund shall be used only for the purposes and disbursed only in the manner provided by this chapter.