Before a drinking water sample is taken, the sampling tap should be clean, free of leaks, and flushed for how long?

Flushing the sampling tap for 2 to 3 minutes is considered best practice to ensure a representative sample of the drinking water is collected. This flushing period is important because it helps to clear the tap of any stagnant water that may have been sitting in the plumbing system, which can have different chemical and microbial characteristics compared to the water that is actively supplied to the tap.

By allowing the water to run for 2 to 3 minutes, any contaminants that might be present at the outlet due to previous water being held in the pipes are flushed away, thus providing a fresher sample that more accurately reflects the current quality of the water supply. This procedure is essential in obtaining reliable samples that can be analyzed to assess the safety and quality of the drinking water.