Any city acquiring a water supply system under the terms hereof shall succeed to all the rights, obligations and property of the metropolitan district, respecting or connected with such system or with the functions of supplying water, unless the purchase contract shall otherwise provide. Any city acquiring a sewage disposal system under the terms hereof shall succeed to all the rights, obligations and property of the metropolitan district, respecting or connected with such system or with the functions of supplying sewage disposal, unless the purchase contract shall otherwise provide. Any city acquiring both a water supply system and a sewage disposal system, or a combined water supply and sewage disposal system, under the terms hereof, shall succeed to all the rights, obligations and property of the metropolitan district, respecting or connected with such system or with the functions of supplying water and sewage disposal, unless the purchase contract shall otherwise provide. The said rights, obligations and property shall include the right to transact a local business and the right to lay, maintain and operate water mains and/or sewers in the public highways, to the extent that such rights have been granted to the metropolitan district by any city, village or township.