At what locations does compliance sampling typically occur in a drinking water system?

Compliance sampling in a drinking water system is crucial for ensuring that water meets safety standards and regulations set by public health authorities. Sampling at the point of entry or point of use is particularly important because it allows for the assessment of water quality as it enters the distribution system and at the taps of consumers.

When sampling occurs at the point of entry, it evaluates water quality at the point where treated water enters the distribution network, providing insight into whether the treatment processes are effective. This sampling can help identify any contaminants that may have been missed during treatment or that may have entered the system after treatment.

Sampling at the point of use focuses on water quality at the consumer's end, allowing for the detection of any changes that could occur due to factors like plumbing issues, storage conditions, or recontamination after treatment. This makes it a critical location for ensuring public health and safety.

In contrast, while other options like source water or treatment facilities and distribution centers or storage tanks are important in the overall water quality monitoring process, they do not focus as directly on what the consumer ultimately receives. Thus, the point of entry or point of use are pivotal for compliance sampling as they reflect the water quality that directly affects public health.