Before taking a bacteriological sample, you should flush the service line.

Before taking a bacteriological sample, you should flush the service line.

• A. True
• B. False
• C. It doesn't matter
• D. Only if water is clear

Answer: (A)

Getting a representative bacteriological sample starts with flushing the service line to clear out water that has been sitting in the pipe. Water in the service line can differ from the distribution system water in bacterial content and disinfectant levels, and it may contain sediments or biofilm. By flushing, you bring water from the main into the sample point and reduce the chance that the test will reflect stagnation or contaminants from the tap or plumbing rather than the system itself. Flushing also lowers any residual disinfectant that could suppress bacteria, helping the test detect what’s actually in the distribution system. In short, it ensures the sample reflects the water customers are receiving, not water that sat in the service line.

Getting a representative bacteriological sample starts with flushing the service line to clear out water that has been sitting in the pipe. Water in the service line can differ from the distribution system water in bacterial content and disinfectant levels, and it may contain sediments or biofilm. By flushing, you bring water from the main into the sample point and reduce the chance that the test will reflect stagnation or contaminants from the tap or plumbing rather than the system itself. Flushing also lowers any residual disinfectant that could suppress bacteria, helping the test detect what’s actually in the distribution system. In short, it ensures the sample reflects the water customers are receiving, not water that sat in the service line.