Sampling for this particular site could be continuous, daily or on a weekly basis.

• A. Treatment Plant
• B. Distribution Main
• C. Storage Tank
• D. Water Well

Answer: (C)

Water quality at a storage tank can change more readily due to water age, stagnation, temperature shifts, and mixing with incoming water. Because of that variability, the sampling plan for a storage tank is often flexible: you might use continuous monitoring with online sensors to track parameters like chlorine residual in real time, or you might take grab samples daily or weekly depending on turnover, risk, and regulatory requirements. This range—continuous, daily, or weekly—fits a storage tank best because its condition can shift quickly and unpredictably, unlike some other sites where sampling schedules are more fixed.

The other sites typically follow more defined schedules tied to their role. A treatment plant is usually equipped with online process monitoring and may rely on continuous data for certain parameters rather than purely grab-sample frequency. A distribution main generally has less frequent sampling (often periodic grab samples) due to flow dynamics and access, and a water well has its own regular sampling cadence focused on groundwater quality.