Before a drinking water sample is taken, how long should the sampling tap be flushed?

Flushing the sampling tap for 2 to 3 minutes before taking a drinking water sample is crucial for obtaining an accurate representation of the water quality. This practice helps to clear out any stagnant water that may have remained in the pipes, which can contain contaminants not present in the water flowing through the distribution system. By flushing the tap for this duration, you ensure that the sample reflects the actual conditions of the drinking water rather than the potentially tainted water that has been sitting in the pipe.

Proper flushing helps to displace any biofilm, sediment, or residue that could be present in the immediate vicinity of the tap, thus providing a more reliable sample of the water that comes directly from the source. This is important for compliance with health standards and for assessing the safety and quality of drinking water.