What Are Water Heater Sacrificial Anode Rods, And How Do They Work?

Water heater

Corrosion is the chemical reaction between metal and water in the presence of oxygen. The sacrificial anode rod draws the corrosive material in your water heater away from the tank and to itself as a "sacrifice." The anode rod corrodes itself rather than the metal tank adding a longer lifespan to traditional water heaters. 

Without this innovative device, the water heater's metal would crumble and stop working very early on. Conventional water heaters have a sacrificial anode rod, while tankless systems do not. There is a lot to know about water heater sacrificial rods, from how they work to detecting if they need replacing, and we will discuss those details here:

How does a sacrificial anode rod work?

The metal anode rod draws minerals present in the water via an electrochemical process by oxidizing faster than the metal of the water heater tank it is protecting. In conventional gas and electric water heaters, there are three common types of metal used in sacrificial anode rods:

  • Aluminum: Most American homes have hard water, so plumbers use an aluminum anode rod to draw the calcium and magnesium to the rod. This action prevents the tank from being further eroded from the harsh minerals. 

  • Magnesium: Most commonly used, magnesium anode rods protect hot water tanks from soft water corrosion. The magnesium anode works the best, meaning it will rust more than the other metal alternatives. It also suggests it will need replacing more frequently to prevent damage to the water heater. 

  • Zinc: Zinc sacrificial anode rods help remove bacteria from the water tank. If a sulfur smell comes from a water heater, switching to a zinc anode rod should rid the tank of odors and unwanted bacteria.

Metal anode options are interchangeable, so it is possible to use an aluminum rod, then a zinc rod, and so on based on the needs of your home. 

Regularly check your water heater anode rod

This system requires preventative maintenance to ensure the longevity of a traditional water heating unit. Check the anode rod every two years to prevent an expensive repair bill. We recommend adding it to your annual plumbing inspection, so it doesn't get missed or forgotten. 

When to replace the sacrificial anode rod

The sacrificial anode rod rusts inside the water heater tank. Some signs of a broken or bad anode rod are:

  • Loud noises or popping sounds occur while heating: An anode rod that needs replacement would have fully corroded. At that time, the tank starts taking the brunt of the sediment accumulation and corrosion. Unusual sounds from the unit indicate deterioration.

  • It smells like sulfur or rotten eggs: Bacteria growing in or around a water heater will start to smell. Get the sacrificial anode rod checked immediately if weird or foul odors start coming from the unit. It could be that it needs replacing or something else that needs attention altogether.

  • You can visually see corrosion on the tank: Rust and cracks are common signs that the anode rod no longer does its job. Any water pooling at the tank's bottom also indicates a need for replacement.

Keep your water heater in optimal condition

Get your water heater, and its components checked every two years to ensure the unit's safety and a longer lifespan. When the water heater or the anode rod needs replacement, do not ignore obvious signs when the water heater is in operation. The sacrificial anode rod can do its job when you follow these tips, and your water heater will work as it should. 

Edwards Plumbing LLC is a licensed and bonded family-owned plumbing team out of Gilbert Arizona, specializing in plumbing emergencies, repairs and renovations. We install and repair plumbing pipes, water heaters, water softeners, sump pumps, sewers, and more. Our competitive rates, honesty, experience serve residential and commercial customers. Call us at (480) 712-2081.