Anode Rods for Suburban OEM RV Water Heaters -- 2-pack This sacrificial Magnesium Anode Rod provides protection against electrolysis action in the water tank, which greatly extends the life of the tank. Generally, under most conditions an anode rod should last at least one year, and should be replaced when most of the material is corroded off It. Although it is not required for water heater operation, the life of the water heater will be shortened without it, and the warranty will become void. Always keep a spare on hand.