The officers or agents of each sanitary district formed under this chapter shall have free access to all premises served by its sewers, at all reasonable hours, for inspection of plumbing and sewage fixtures, to ascertain the quality and quantity of sewage discharged and the manner of discharge, and to enforce this chapter and the rules and regulations prescribed by the trustees of the district.   [PL 1979, c. 541, Pt. A, §273 (AMD).]