What Is a Sacrificial Anode?

Think of it as a decoy: the anode volunteers to be corroded so your tank isn’t. It’s the single most important maintenance item in a storage hot water system, and also the most ignored.

Why It Matters

• The anode is designed to be replaced roughly every 5 years. Most homeowners have never been told this.
• Once it’s fully sacrificed, the electrolysis in the water starts eating the inside of the steel tank instead.
• This is exactly why electric hot water cylinders commonly fail around the 10-year mark: five years protected, five years corroding.
• Replacing the anode on schedule can greatly extend the life of your tank, for a small fraction of a replacement system’s cost.

The Warning Sign It’s Too Late

Sediment and rust flowing from your hot taps (over you in the shower, into the sink when washing dishes) means the tank’s interior is already corroding. At that point the tank is on borrowed time.

Common Mistakes or Misunderstandings

• “My tank has a 10-year warranty, so it lasts 10 years.” Warranties usually require anode maintenance in the fine print, and 10 years is the unmaintained lifespan, not the potential one.
• “Stainless steel tanks need this too.” They don’t: stainless tanks are highly rust-resistant and don’t rely on a sacrificial anode, which is why we often recommend them at replacement time.
• “Rusty hot water just needs a flush.” Flushing removes sediment, but rust from the tank wall means corrosion has started; no flush reverses it.

When to Call a Plumber

If your electric storage system is 5+ years old and the anode has never been replaced, book the swap: it’s a quick service call. If you’re already seeing rusty hot water, get the tank assessed before it starts leaking.