How often should you replace your water heater's anode rod?

Why bother

The rod rusts so the tank doesn't. Spent, and the tank's next. This is an essentials-tier job. Skip it and you're inviting the expensive kind of problem, or the dangerous kind.

Why it's a range

Hard water and a softener both eat the rod faster, so check it at three years and you'll learn your own house's pace. Four to five years is the usual span. Nobody sells you an anode rod, which is roughly why nobody mentions it.

What the job involves

1. Cut the power or gas to the heater and shut the cold water supply, then drain a few gallons off the bottom so the level drops below the rod port. Don't skip the draining, the rod sits in the top and you want it above the waterline.
2. Find the hex head on top of the tank (sometimes it's hiding under a plastic cap, sometimes combined with the hot-water outlet) and break it loose with a 1-1/16 inch socket or a pipe wrench. Years untouched, it'll be tight; a breaker bar earns its keep here.
3. Haul the old rod out, wrap the new one's threads with plumber's tape, and thread it in. Snug, not gorilla-tight.
4. Refill the tank, open a hot tap to let the air burp out, check the rod head for drips, then restore the power or gas.

Do it yourself, or pay someone?

Yourself, if you're handy and there's clearance above the tank: the rod's $20-$50 and the job is mostly muscle. A low ceiling wants a flexible rod, and a seized rod wants patience. A plumber runs about $200-$300 for the swap.

What skipping it costs

$900-$2,200 to replace the whole tank (average about $1,340) is what waits at the end of ignoring this. The anode rod is a length of metal that corrodes on purpose so the steel tank doesn't; once it's fully eaten and nobody swaps it, the tank starts rusting from the inside out. That can't be patched, so the heater goes years before it should, and a rusted-through tank can dump 40-50 gallons onto the floor on its way out, water-damage cleanup stacked on top of the new unit. A $20-$50 rod every three to five years is what stands between you and that bill.

Signs it's overdue

• Hot water comes out rusty or off-color. The tank steel has started corroding, which means the rod's already given up.
• A rotten-egg or sulfur whiff on the hot water, usually a spent magnesium rod reacting with bacteria in the tank.
• Popping, hissing, or banging from the tank, sediment piling up while the rod no longer does its job.

When to start thinking about it

Give yourself about 14 days' notice. That's when Grumpty starts grumbling, so it doesn't land on you the day it's due. Mark it done and Grumpty sets the next one, every 48 months, so you can go back to forgetting it exists.

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