The Secret to Making Your Water Heater Last Decades
![A Little-known Component In Most Water Heaters Holds The Key To Decades Of Service [Photo Courtesy Of Larry Weingarten]](https://www.energyvanguard.com/wp-content/uploads/2025/05/new-and-old-anode-rods-1200.jpeg)
A water heater is a significant investment, no matter what kind you have. When you install a heat pump water heater, it’s even more important to keep it going as long as you can. So how do you do that? Well, there’s this one component you should check regularly—or have someone check for you if you don’t want to take an accidental shower like I did this past weekend. Do you know what it is?
But before we get to that, you probably are wondering about that shower, so here’s a 27 second video showing me creating an accidental fountain in my mechanical room.
The primary cause of failure
It’s not the only cause, but corrosion inside the tank is probably what causes more water heaters to fail than anything else. (See this page at the Water Heater Rescue site for more.) Most tank water heaters have a steel tank with a protective glass lining on the inside. But that glass lining isn’t perfect. When the water is able to reach the steel behind the glass, the tank starts corroding.
Water quality plays a role, too. The mineral content, which affects the hardness or softness of the water, is an important factor. And if you use a water softener, you’re adding ions that can make things worse. Way worse, in fact. Larry Weingarten told me he’s seen anode rods deplete in as little as 6 months when someone is too aggressive with their water softening. Then there are sulfate-reducing bacteria that can do some damage.
What these things have in common is electrical activity, which leads us to…
The sacrificial anode rod
Cathodic protection is an established method of protecting metals from corrosion. You can read all about how it works and what some of the other applications are on the Wikipedia page for that topic. What it means for you is that water heaters with glass-lined steel tanks have an anode rod.
Not all storage water heaters have anode rods, though. Some have plastic tanks. Some have stainless tanks. Those don’t corrode from contact with water and thus do not need anode rods.
The anode rod is connected electrically to the tank, which acts as the cathode. But it’s the sacrificial anode rod that takes the abuse from the ions and minerals in the tank. And those chemical reactions, over time, destroy the anode rod. That, of course, is why it’s called sacrificial.
The problem here is that almost no water heaters ever get their anode rod checked and replaced. Once the outer material on the rod dissolves away, the anode rod provides no protection to the tank. At that point, it’s only a matter of time.
How often do you need to change the anode rod?
It depends on water quality. You may live in an area where anode rods waste away in as little as six months. Or maybe yours will last 15 years. I’ve had my water heater installed for nearly six years now, and you’ll see below what the original anode rod looks like.
If you know how long the last water heater lasted, that may give you a clue to your water quality and the potential life span of your anode rod. When I replaced our water heater in 2019, the previous one had been going for 20 years. I’m pretty sure it had had no maintenance. The anode rod, had I checked it, probably would have had little left but the center wire. But since it kept that water heater alive for 20 years, that’s an indication that our water isn’t hard on water heaters.
I checked my anode rod
I won’t write a lot here because the video below covers most of the important points about checking an anode rod. You’ll also find in the video an explanation of what might have caused the accidental fountain I created and a cautionary note for DIYers.
So how was the anode rod in my heat pump water heater? It’s been doing its job in there since I had the water heater installed in September 2019. That means I let it go for 5.7 years before checking it for the first time. The photo below shows what it looked like. I couldn’t pull it all the way out because of the ceiling height in my mechanical room, so I put three separate photos together in a panel.
For comparison, you can look at the photo below. Mine is certainly not in the pristine state of a new one, but it’s far from the ready-for-replacement state.
Tips for checking the anode rod
Here are some things to do or be aware of when checking and replacing the anode rod, most of which I covered in the video above:
- Turn the power off of electric water heaters. Set a gas water heater to pilot or off.
- Close the valve in the water heater supply line.
- Open a hot water tap to drain some water from the tank.
- Drain a bit of water from the bottom of the tank.
- Don’t drain too much water, though, because you want the tank to be heavy enough to resist spinning when you try to loosen the anode rod.
- Close the hot water outlet valve if you have one.
- Continue draining a little water from the bottom of the tank to ensure the pressure is relieved.
- Use a 6 point, 1 1/16″ socket with a 1/2″ drive breaker bar or ratchet.
- If that’s not enough, slide a steel pipe over the breaker bar/ratchet as I did in the video above.
- When closing it up, wrap the threads with 6 wraps of teflon tape and tighten the rod.
- Check for electrical continuity between rod and tank.
- Open the valve and check for leaks when the tank fills up again.
There’s a lot of information online about anode rods, so look around, too. The Water Heater Rescue site is a great resource for lots of hot water topics.
What are you waiting for?
If you don’t know how long it’s been since you checked your anode rod—or had it checked by someone else—then it’s probably time to check it. So what are you waiting for?
Allison A. Bailes III, PhD is a speaker, writer, building science consultant, and the founder of Energy Vanguard in Decatur, Georgia. He has a doctorate in physics and is the author of a bestselling book on building science. He also writes the Energy Vanguard Blog. For more updates, you can follow Allison on LinkedIn and subscribe to Energy Vanguard’s weekly newsletter and YouTube channel.
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https://energyhandyman.com/critical-details/water-pressure-and-thermal-expansion/
There’s more than one secret, if you have a check valve, you need to control your water pressure and control the thermal expansion. In Raleigh, water heaters often crack (the glass inner liner) during the very first heating cycle because a 1.8 gallon thermal expansion tank is drastically too small. Other folks have a water heater that lasts 20 years simply because they have leaking toilets and no pressure can build up that is in the danger zone 🙂 hiss hiss hiss every 10-15 minutes for 20 years. The basis of TXPTs is “check valves” and necessary water conservation. And yes, water pressure reducing valves often act as backflow preventers.
Adam: Yes, indeed, there are many things that can cause a water heater to fail. Tank failure because of corrosion is said to be the number one cause, but keeping the water pressure too high can cause failures.
re: clearance height requirement to remove/replace anod rod –
have heard of ‘segmented anod rods’ purported to address this issue. Thanks for any insights you can share on such a product.
Kevin: Yes, segmented anode rods do address the lack of height issue. When it’s time for me to replace mine in 10 years or so, that’s probably what I’ll use.
For getting the old rods out, you have some options. One is to wait until all that’s left is the central wire, but then you’ve waited too long. A second is to cut the rod so you can remove it. And a third, which Larry Weingarten told me about, is to pull the rod up, bend it gently, then pull some more and bend again. Do that until you can pull it all the way out.
Why 6 wraps of teflon tape rather than, say, 5 or 7? And what’s your explanation for a Rheem installed in 1979 that has never leaked with the original anode?
Tim: 6 wraps because that’s what Larry Weingarten said is best. And he’s got WAY more experience than I do.
A water heater that’s been going since 1979 could have lasted that long because it has a stainless steel tank. Are you sure it has an anode rod? Or maybe the water quality there is exceptional?
The house actually had 3 water heaters when it was built in 1979. I don’t know whether any of them had anode rods, but 2 of the 3 leaked and were replaced.
Forty years ago, when our company manufactured and sold water heating heat pumps we changed a ton of tanks and found many of the older tanks with virtually no anode left. If we added our remote WHHP to an existing tank we always checked the anode and some were difficult due to the head space above the ceiling. Others were difficult because the anode nut was fragile or just plain stuck.
The workaround was to add an anode to the hot water discharge port. We’d remove the hot water nipple and insert a segmented anode with a 3″ or 5″ nipple attached. We found this an easy and inexpensive alternative to changing the tank or wrestling unnecessarily with the old anode rod.
I believe these are still sold at building centers or online and would be a good idea for any tank regardless of age or water conditions. If nothing else it’s low-cost belt and suspenders.
Mac: Thanks for pointing out that you don’t have to go back in the same place with a new anode rod and that segmented rods overcome the ceiling height problem. Those are great tips!
Unfortunately, the neither the sellers of hot water tanks nor the installers ever mention maintenance. Your article is helpful and needed. An EcoKing will replace my double glass lined Giant tank in Whistler/Creekside someday and maybe my Rheem in Tacoma. However, mountain water keeps both in good shape, and the Tacoma Public Water Department treats the municipal water unlike Whistler. A good public works department is essential, not that I had a clue. Real world applications are not emphasized in graduate school.
Dale: Yeah, I think plumbers who recommend anode rod checks are few and far between. That’s unfortunate since it’s such a critical part of maintenance.
What do you think of the powered anode rods?
Cody: I’ve heard they’re great. As long as they remain powered, they’re supposed to protect the water heater as long as it lasts with no need for replacement.
What are your thoughts on active anodes? I have about a foot of clearance above my water heater, so one of those short active anodes would make it a LOT easier to replace. I can (hopefully) either bend or saw the old one to get it out, but I can’t reasonably use the same tactic to install a new one.
But sales hype aside, will an active anode actually protect the tank? I was thinking that the whole point of a sacrificial anode was that it actually plates a small amount of metal onto the less “noble” tank. I don’t see how that would work with a powered titanium anode (as used by the brand that dominates the internet). I’d love to gain your scientific perspective.
I have used the anodes with a brass nipple attached, either the segmented version or straight, depending on clearance. Use in place of Hex head as they are easier to replace. Add a boiler drain or hose bib to the nipple outlet to relieve any static water pressure in the house piping system., (and it can be used as a hot water source). I have taken a few unscheduled showers in the past.
Big smiles on your self-effacing video, Allison. 😀 I thought things like that only happened to me.
When my WH started turning under the influence of a 6’ cheater bar, I finally borrowed an air compressor and used a 1/2” impact wrench to remove the anode.
Worked a treat.
Wish I could change the rod in our HWH but it’s in a hallway closet and consequently it’s physically impossible to remove without removing the HWH itself. Grrrr.
JC: You don’t have to replace the existing rod with one in the same place. See the comment by Mac Sheldon here.
Thanks to all for the information and comments …one comment I remember about water heater anodes and transporting water heaters.
The anode should be checked the first -year service in order to verify that it is operating properly.
It should look like it is being nibbled on by an animal; thus, performing its sacrificial duty. If it looks as if has discolored to a dark hue and there is no loss of metal to the anode, then the anode is likely not working.
This can be a rare OEM issue or damage during transporting lying down in the truck; the anode rod is subject to stress at the tank connection due to the leverage of the long anode. In some anodes the connection made between the anode’s steel plug and the anode material itself is subject to failure when transported improperly. Softened water will show anode degradation within a few months, thus working properly. I have pulled anodes from warranty leakers and found the anodes discolored but intact.