That water districts duly organized under the laws of the state of Washington shall have the following powers in addition to those conferred by existing statutes. Whenever any water district shall have installed a distributing system of mains and laterals and as a source of supply of water shall be purchasing or intending to purchase water from any city or town, and whenever it shall appear to be advantageous to the water consumers in said water district that such city or town shall take over the water system of the water district and supply water to the said water users, the commissioners of said water district, upon being authorized as provided in RCW 57.08.030, shall have the right to convey such distributing system to any such city or town: PROVIDED, Such city or town is willing to accept, maintain and repair the same: PROVIDED, FURTHER, That all bonded and other indebtedness of said water district except local improvement district bonds shall have been paid.