What is a sacrificial anode?
A metal rod, typically made of magnesium or aluminum, installed inside a hot water tank that corrodes preferentially to protect the tank steel from rust and extending its lifespan.
A sacrificial anode is a metal rod installed vertically inside a hot water tank, usually made from magnesium or aluminum. Its role is to corrode in place of the tank itself, slowing the natural rust process that occurs when steel is exposed to water and oxygen.
Hot water tanks are vulnerable to internal corrosion because the steel walls sit in constant contact with heating water. A sacrificial anode works through a chemical process: because it is more reactive than the tank steel, water corrodes the anode preferentially, sacrificing itself to extend the life of the tank. This is why the rod is called "sacrificial" - it deliberately degrades to protect what surrounds it.
Over time, the anode rod becomes consumed and must be replaced. Most tanks need a new anode every 3-5 years, depending on water quality, tank size, and temperature settings. A heavily corroded or completely depleted anode leaves the tank exposed to rust, which leads to leaks and premature tank failure. Plumbers regularly inspect anode condition during maintenance visits, and replacing it is a routine preventive task that can add years to a tank's service life. Hot water system specialists can assess whether your anode needs replacement or if a full tank replacement is necessary.