How often should you check a water heater anode rod?
Every 2 years.
How to do it
Unscrew the anode rod from the top of the tank. Replace it if it is worn to the core wire or thinner than a pencil.
Why it matters
The anode rod corrodes so the tank does not. A $30 rod can add years to a tank.
Recommended interval: every 2 years, per Bradford White.
General guidance for a typical home; the manufacturer's instructions come first.