§ 410. Undertakings to be self-supporting. The governing body of a municipality issuing bonds to carry out any of the purposes of this article shall prescribe and collect reasonable rates, fees, tolls or charges for the services, facilities and commodities of such undertaking, and shall revise such rates, fees, tolls or charges from time to time whenever necessary so that such undertaking shall be and always remain self-supporting. The rates, fees, tolls or charges prescribed shall be such as will produce revenue at least sufficient (a) to pay when due all bonds and interest thereon for the payment of which such revenue is or shall have been pledged, charged or otherwise encumbered, including reserves therefor, and (b) to provide for all expenses of operation and maintenance of such undertaking, including reserves therefor.