The council of any borough or incorporated town within this Commonwealth may, upon request of the commissioners of water-works, issue bonds for the extension of water-works or the erection of new water-works. Said bonds shall be issued in the form and manner now provided for by law, and shall be designated “water-works bonds.” They shall be delivered to said commissioners, from time to time, upon their requisition, after the commencement of the work for the payment of which such bonds were issued. Each such requisition shall be accompanied by a detailed statement of the work done and materials purchased. Said bonds shall not be sold for less than par and the proceeds thereof shall be applied to the purposes for which said bonds were issued, and no other.