Potable water systems or any part thereof installed or repaired shall be disinfected in accordance with one of the following methods before it is placed in operation:
1. The system, or part thereof, shall be filled with a solution containing 50 parts per million of available chlorine and allowed to stand six hours before flushing and returning to service;
2. The system, or part thereof, shall be filled with a solution containing 100 parts per million of available chlorine and allowed to stand two hours before flushing and returning to service;
3. In the case of a potable-water storage tank where it is not possible to disinfect as provided in subsections 1 and 2, the entire interior of the tank shall be swabbed with a solution containing 200 parts per million of available chlorine and the solution allowed to stand two hours before flushing and returning to service.