There shall be a board of water commissioners consisting of three (3) members elected for terms of three years each, so arranged that one term shall expire each year. The board of water commissioners shall have general charge of the care and management of the municipal water system, and of all property of the town relating thereto. The board of water commissioners shall have all of the powers and duties which are given to boards of water commissioners under the constitution and laws of the Commonwealth of Massachusetts, and such additional powers and duties as may be authorized by the charter, by by-law or by other vote of the town meeting.