Water heater anode rods
Quick answer
The anode rod is a piece of metal that sacrifices itself to protect the steel tank. Change it every 3 years and a water heater could last 25 to 50 years.
How it works
Your water heater is made of steel, and steel rusts. To stop the tank rusting and eventually leaking, anode rods are installed. The anode gives its own electrons to the steel to keep it rust and decay free.
Think of wall spackle filling a nail hole. The anode does the same job for the tank, and like a can of spackle, it runs out. Rods can be changed every few years, or larger rods fitted at installation.
Why it matters most
Replacing a $30 to $50 anode rod can add years to a heater. All the other maintenance steps combined aren't half as important as replacing your anode rods.
Rather we did it?
Anode replacement