The district shall provide for the payment of the principal of and interest on the bonds by the levy and collection of taxes upon all property in the district subject to taxation by the district without limitation of rate or amount as provided in Sections 29121 and 29122 of this part, except that such taxes need not be levied to the extent that the district deposits in the treasury set apart for that purpose moneys derived from surplus revenues or any appropriations which may be made to it for that purpose or from any other funds howsoever derived.