Small and medium sized utilities are deemed to have optimal corrosion control if they meet lead and copper levels for how many consecutive sampling periods?

Small and medium sized utilities are deemed to have optimal corrosion control if they meet lead and copper levels for how many consecutive sampling periods?

• A. Two consecutive sampling periods
• B. Three consecutive sampling periods
• C. Six consecutive sampling periods
• D. Nine consecutive sampling periods

Answer: (A)

The idea being tested is that optimal corrosion control is shown by sustained performance, not a one-time result. If lead and copper levels stay at or below the action levels for two back-to-back sampling periods, it demonstrates the corrosion control program is consistently effective over time, accounting for seasonal and water-quality variability. In practice, those sampling periods are typically six months each, so two consecutive periods cover about a year, giving a stable confirmation of performance. Choosing two periods rather than more (like three, six, or nine) reflects the requirement to prove sustained control without extending the verification process longer than necessary.

The idea being tested is that optimal corrosion control is shown by sustained performance, not a one-time result. If lead and copper levels stay at or below the action levels for two back-to-back sampling periods, it demonstrates the corrosion control program is consistently effective over time, accounting for seasonal and water-quality variability. In practice, those sampling periods are typically six months each, so two consecutive periods cover about a year, giving a stable confirmation of performance. Choosing two periods rather than more (like three, six, or nine) reflects the requirement to prove sustained control without extending the verification process longer than necessary.