All income and revenue derived from or obtained in the course of the operation of the Municipal waterworks shall be placed to the credit of the Water Revenue Fund, out of which all the costs and expenses of the operation of the waterworks shall be paid, as well as an amount sufficient to pay the interest, principal and charges on bonds which have been or may be issued under authority of ordinances which provide that the interest, principal and charges on such bonds shall be paid out of the income or revenues of the waterworks. Also, there shall be paid out of the Water Revenue Fund such other and further items as may be properly charged pursuant to law against the income and revenue of the waterworks.