How frequently shall the interior of water tanks with corrosion protection be inspected?

• A. Every 2 years
• B. Every 3 years
• C. Every 5 years
• D. Every 10 years

Answer: (C)

Regular interior inspections for corrosion-protected water tanks are scheduled to balance detecting coating or lining issues with practical maintenance timelines. When protection is in place, deterioration tends to progress more slowly, so checking about every five years is a sensible interval. This allows inspectors to verify coating integrity, identify any delamination or hidden corrosion, and confirm that the protection remains effective without inspecting too often.

Inspecting more frequently (every couple of years) would add unnecessary cost unless signs of trouble appear. Waiting longer (every ten years) could let problems develop unseen between checks. Therefore, five years is the appropriate frequency.