Any employee of the water department of any municipality, including any employee having supervision or regulation of the water department, who shall have served honorably in the department for a period of twenty-five years and reached the age of sixty years, shall, upon his own application, be retired on half pay. Any such employee who shall have served honorably for a period of twenty years and reached the age of sixty-five years shall be retired on half pay.
N.J.S. § 43:13-30