Only persons authorized by a permit shall turn on or shut off the water supply at any stop cock at the main or at the curb or allow any person in his or her employ so to do, nor shall he or she have in his or her possession any tool or instrument for that purpose. Only persons authorized by a permit will be allowed to tap any main or do any excavation or any street work in connection with the laying, installation, extending or repairing of any water service, water pipe or water appurtenances without the permission of the Water Department.
(`89 Code, § 161.120)