What is the process of obtaining a first draw sample?

Obtaining a first draw sample involves collecting water from a tap that has not been used for a specified period, usually several hours, to ensure that the sample reflects the water that has been sitting in the plumbing system. This process helps to identify potential contaminants that could leach from pipes or fixtures into the water supply. Collecting the water immediately after opening the faucet ensures that the sample is representative of the water quality in the system just prior to usage, effectively capturing any issues that may exist due to stagnant conditions.

In contrast, letting the tap run for two minutes would likely flush out any contaminants that may have been present from the plumbing, resulting in a sample that does not accurately reflect actual water quality. Filling a container from a water storage tank may introduce variability based on how long the water has been stored in that tank, which is not suitable for a first draw sample that aims to reflect plumbing conditions. Using water from a refrigerator filter also does not represent the first draw from the tap itself and is likely to affect the sample by filtering out certain substances, again compromising the integrity needed for accurate sampling of stagnant water conditions.