(3)A local authority may, with the previous sanction of the Government, by public notice, declare any lake, stream, spring, well, tank, reservoir, pond or other source of water-supply, whether within or without the limits of its local area (other than a source under the control of the Government), from which water is or may be made available for the use of the public in the local area for domestic purposes, to be a source of public water-supply for such purposes and every such source shall thereafter be under the control of the local authority, only to the extent necessary for such purposes.
