Why does an inspector look at the anode access on a water heater where visible?

A storage water heater's steel tank is protected by a sacrificial anode rod — a magnesium or aluminium rod that corrodes preferentially so the tank does not. It is consumed over years, and once it is gone the tank itself becomes the sacrificial element and corrodes from the inside out until it leaks, typically without warning and typically all at once. Replacing an anode is inexpensive and extends tank life considerably, but it is maintenance almost nobody performs, so most tanks fail with an anode long since consumed. The inspector's role is bounded by access: the anode's condition requires removal to assess, so what the inspector can do is note whether the access port is present and visible, note the tank's age, and mention anode replacement as maintenance the client may not know exists.

The anode corrodes sacrificially so the tank does not, and once it is depleted the tank itself begins corroding toward eventual failure. That is why its presence and condition matter to tank life.

Storage water heaters use a sacrificial anode rod to protect the glass-lined steel tank from corrosion. Anode life varies with water chemistry and usage, and depletion leads to tank corrosion and eventual leakage.

The Rod Rusts So the Tank Does Not. When the rod is gone, the tank takes over the job — and it only gets to do it once.

Note that assessing the anode requires removing it, which is outside the inspection. Reporting its existence and recommending checking is the appropriate treatment.

• •Confusing the anode with electrical bonding
• •Attempting to assess anode condition without removal
• •Omitting anode replacement from maintenance discussion on an ageing tank