What interval is specified for checking the accuracy of water level indicators in tanks?

• A. every 1 year
• B. every 3 years
• C. every 5 years
• D. every 7 years

Answer: (C)

The key idea is understanding how often a water level indicator in a tank is likely to drift out of calibration. Water level indicators are relatively simple devices, and their readings don’t typically change quickly with normal use. Because of that slow drift, they’re checked less frequently than more critical or quickly failing components, and five years is a reasonable interval to verify accuracy, calibrate if needed, and catch any gradual wear before it affects operation.

To test, you compare what the indicator shows with the actual water level, inspect the mechanism (float, linkage, sight tube, seals, mounting) for wear or damage, and calibrate or replace parts if the reading is out of tolerance. This approach keeps maintenance practical while maintaining confidence that the tank will show the correct level when needed.

Choosing a shorter interval (like every year or every few years) would be more resource-intensive without a corresponding gain in reliability for this item, while a much longer interval could let drifting go unnoticed.