Every water heater has an anode rod. Water corrodes the inside of steel tank water heaters. The anode rod sacrifices itself to protect the tank. As it deteriorates it should be replaced, or the tank will corrode and eventually leak. Check your anode rod every 2 years as the anode rod's life depends on a few variables, including water quality, tank use, water temperature, and tank quality. The Water Heater Smart Blue Lightning anode rod will help avoid early tank failure. The segmented design allows for replacement in tight spaces. The anode rod can be cut in length to fit short water heaters. The Blue Lightning rod is made of environmentally-friendly Magnesium, with durable, corrosion-resistant, stainless steel links.