Mass. Gen. Laws ch. 111 § 26G
In any city, town or district which accepts the provisions of this section notwithstanding the provisions of section seventeen of chapter two hundred and sixty-eight A, a septic system installer who is appointed or elected to the board of health may engage or work at the business of septic system installation within the area over which the board of health has jurisdiction while serving as a board member; provided, however, that neither the board of health member nor the board shall inspect a septic system installation done by said board of health member, or said member's partner, employer, employee or co-employee. The inspection of work so done shall be performed either by the board of health of another city, town or district or by a special assistant health agent who is appointed solely for the purpose of performing such inspections by the mayor of a city, the board of selectmen of a town or the governing board of a district. If the board of selectmen also serves as the board of health, said septic system installer shall not participate in the appointment of special assistant health agent.
This section shall take effect upon its acceptance in a city, by the vote of the city council, subject to the provisions of the charter of such city; in a town, by a vote of town meeting; in a municipality having a town council form of government, by a vote of the town council, subject to the provisions of the charter of such municipality; and, in a district, by the vote as above provided of the cities and towns of the districts.
Mass. Gen. Laws ch. 111, § 26G