When selecting a sampling point, why should you avoid using certain faucets?

When selecting a sampling point, it is essential to avoid using certain faucets primarily because they can introduce contaminants into the water sample. Faucets that are not regularly used or have been inactive for a period may harbor biofilms or other substances that can leach into the water, compromising the quality of the sample.

Contaminants can originate from various sources, such as old plumbing materials, sediments, or biological growth, which may accumulate in rarely-used fixtures. Obtaining an uncontaminated sample is crucial for accurate testing and analysis of water quality, as even minor contaminants can significantly impact the results and lead to incorrect conclusions about the water's safety or compliance with health standards. Therefore, selecting a sampling point that minimizes that risk is vital to ensure the integrity of the water quality testing process.