Section 16. During a state of water emergency, declared under section fifteen, if the department has approved a plan designed to bring about an expeditious end to the emergency, a water company, public agency or authority of the commonwealth or its political subdivisions which is the operator of a public water system affected by the emergency may, for such periods of time as may be approved by the department, not to exceed six months cumulatively in any twelve month period, take by eminent domain under chapter seventy-nine the right to use any land for the time necessary to use such water, or purchase water from another public water system; provided, however, that during a state of water emergency affecting the water system of the Massachusetts Water Resources Authority, such power of eminent domain may be exercised by the division of watershed management of the metropolitan district commission. Any operator of a public water system may, for such periods of time as may be approved by the department, sell to any water company, public agency or authority of the commonwealth or its political subdivisions, which has been authorized to make purchases of water pursuant to this section, such volumes of water as may be available for sale from time to time.

No taking, purchase or sale shall be made pursuant to this section unless the department issues an order, pursuant to section seventeen, authorizing the taking, purchase or sale. Nothing in this section shall exempt the operator of a public water system from any provision of this chapter or of any regulations issued hereunder.

No taking, purchase or sale shall be made pursuant to this section unless, in the case of cities, the city council has voted to authorize the taking, purchase or sale, or, in the case of towns and water supply and fire and water districts, the taking, purchase or sale has been authorized by a vote of the voters at a town meeting or a district meeting, or, in the case of water companies, notice of such taking, purchase or sale, including a copy of plans and specifications, has been given to the city council or to the board of selectmen of the city or town, as the case may be, in which the affected water source is located, by certified mail at least ten days prior thereto.

Pursuant to any taking, purchase or sale made pursuant to this section, temporary pipes and other works may be installed in any city or town, provided that the installation or repair of such pipes or other works or along any highway shall be accomplished with the least possible hindrance to public travel, and shall be subject to the direction and approval of the officers or departments in charge of the maintenance of said highway where applicable.