To have the exclusive right, at all times, to supply the city with water, and such persons, partnerships and corporations therein as may desire the same, at such price as may be agreed upon, and for the purpose to have, at all times, the unrestricted right to make, erect and maintain all proper works, machinery, buildings, cisterns, reservoirs, pipes and conduits for the raising, reception, conveyance and distribution of water, or, in territory not supplied with water, to make contracts with and authorize any person, company or association so to do, and to give such person, company or association the privilege of furnishing water, as aforesaid, for any length of time, not exceeding ten years.