The interior of all other types of tanks shall be inspected every ______.

• A. 3 years
• B. 4 years
• C. 5 years
• D. 2 years

Answer: (C)

Regular interior inspections of water storage tanks are done to detect problems that aren’t visible from the outside—things like internal corrosion, coating breakdown, pitting, sediment buildup, or signs of leaks that could reduce capacity or threaten water quality. For most tank types categorized as “other types” in the standard, the required interval is five years. This 5-year window provides a practical balance: it’s long enough to avoid unnecessary disruption, yet frequent enough to catch developing issues before they become serious or require more extensive repairs. If a tank is in a harsher environment or has special service, more frequent inspections may be specified, but the baseline for these tanks is every five years.