Waterworks which are jointly constructed, maintained, controlled or operated by two or more municipalities may be financed by the issue and sale of bonds and collection of water charges, as provided in Sections 37-106 through 37-109 of this title. The governing bodies of such municipalities are hereby specifically authorized to enter into agreement and contract as to the amount of each municipality's indebtedness and proportionate share of cost of construction, maintenance, control and operation of any waterworks jointly acquired under the provisions of Section 37-124 of this title; provided that in all cases where a proposition is submitted to the registered voters of any municipality for the voting of bonds to defray costs of such a joint contract, the election notice and ballot shall so state.