Rheem vs AO Smith: Which Water Heater Stands Out?

It’s wild how much you depend on your water heater—until you’re shivering under a cold shower before work. If you’re stuck between Rheem and AO Smith when it comes to repairs or buying a new tank, you’re not alone. These two brands run the show in water heaters across the U.S., popping up in suburban garages, city apartments, and everywhere in between.

What really separates these giants? It’s not just some logo on the side of the tank. Factors like how long your water heater actually lasts, how often it breaks down, and how much of a hassle or cost it is to fix—that’s where things get real.

Here’s where it gets useful: not every home or hot water routine needs the same thing. A family cycling through midnight laundry loads has different needs than a bachelor who only uses hot water for showers. If you’ve ever had to hunt for parts on a weekend, or waited days for a tech to show up, you know: small differences between brands can turn into big headaches fast. And when a repair bill shows up, nobody’s cheering.

I’m going to break down the things that genuinely matter—how Rheem and AO Smith stack up day to day, what lasts, what needs repairs, and how each handles pretty common issues like leaky tanks or faulty thermostats. If your goal is to stay warm, save money, and spend less time fixing stuff, you’re in the right place.

• Brand Reputation and Popular Models
• Build Quality and Longevity
• Energy Efficiency and Features
• Repair, Maintenance, and Warranty Insights

Brand Reputation and Popular Models

People talk a lot about household brands, but for water heaters, Rheem and AO Smith aren’t just names—they’re the top dogs. When it comes to market share, these two are way ahead of the pack. They’ve both been kicking around since before most of us were born (Rheem’s been in the business since 1925, AO Smith since 1874), so there’s a ton of real-world feedback out there.

Here’s a quick look at how they stack up in U.S. homes:

When people leave reviews on big retail sites or chat with repair pros, you’ll see some clear patterns. Rheem gets a lot of love for affordable, easy-to-find replacement parts and a generally solid rep for their electric tank models. AO Smith is often the go-to for commercial setups and high-efficiency systems—think hotels, gyms, and big family homes. That’s because their hybrid and commercial models have legendary durability, according to a 2023 industry report by Plumbing & Mechanical Magazine.

Popular models you’ll probably run into if you’re shopping around or scheduling a repair include:

• Rheem Performance and Performance Platinum (gas and electric tank)
• Rheem Prestige (tankless, high-efficiency option)
• AO Smith Signature and Voltex (hybrid electric)
• AO Smith ProLine XE (tank and tankless lines with lots of sizes)

Both brands put out dependable workhorses for families, apartments, and businesses. If you’re replacing an old unit, the odds are good you already have one of these names in your basement.

Build Quality and Longevity

When you’re talking water heaters, that “set it and forget it” feeling mostly comes down to build quality. If you go with Rheem or AO Smith, you’re dealing with brands that stick to solid engineering—nothing flimsy or likely to fall apart in a couple of years. But there are important differences to keep in mind if you want fewer cold showers and less time on the phone with repair crews.

Let’s start with tank materials. Both brands mainly use glass-lined steel tanks, which are the industry standard for stopping rust and leaks. But AO Smith has a bit of a reputation for thicker glass lining and quality control in their welds. That means their tanks are less likely to start leaking early on. Rheem’s tanks are still solid, but over the years—especially with their budget models—folks have reported more small leaks in the 7-10 year range.

One spot where Rheem deserves credit is with their anode rods. These metal rods protect your tank from corrosion. Rheem tends to use longer or dual anode rods even in regular models, which slows rusting. AO Smith sometimes uses single anode rods, especially on their entry-level heaters, which means you might be replacing or inspecting rods a bit sooner.

If you’re curious about how long these things last, here’s a rough breakdown for tank-type (not tankless) heaters from each brand:

Another thing: AO Smith usually gets praise from plumbers for their heavier tanks and metal drain valves, which hold up better if you flush your heater yearly (you should!). Rheem uses plastic drain valves on a lot of units, which can crack or jam over time. If you’re the kind of person who stays on top of maintenance, this might not matter much, but if you’d rather set things and walk away, this is good to know.

Looking for something low-maintenance? AO Smith’s tanks seem to go the distance with less fuss, especially if your area has hard or mineral-rich water. But the Rheem lineup is hardly a gamble—just keep a closer eye on anode rods and drain valves, and you’ll get a solid run out of them.

• Check your heater’s anode rod every 2-3 years—replace early to extend lifespan.
• Flush that tank yearly to remove build-up, especially important if you have hard water.
• If picking a model, pay extra for stainless or metal drain valves instead of plastic.

Don’t just set and forget—small tweaks and basic care can push either brand to 15+ years. The choice comes down to whether you want “extra tough” with less maintenance (AO Smith) or “easy part replacements” and solid middle-of-the-road performance (Rheem).

Energy Efficiency and Features

If you’re thinking about long-term savings beyond just picking the cheapest water heater, pay attention to energy efficiency and the extras that come with each brand. Rheem and AO Smith both push new tech to squeeze every dollar out of each gallon, but they don’t go about it the same way.

First, the basics. Look for the Uniform Energy Factor (UEF) on both brands. For standard 50-gallon electric tanks, AO Smith usually lists UEF ratings around 0.92 to 0.95, while Rheem often sits at 0.92 to 0.93. If you want the high-efficiency stuff, both brands make heat pump hybrids, and that’s where the real savings start piling up—hybrids can go above 3.4 UEF, which is almost four times more efficient than plain old electric.

Here’s what stands out: Rheem’s smart controls and WiFi work without much hassle. I tried setting up a Rheem EcoNet app with our house tank in 2024—it took less than 10 minutes, and I set vacation mode and got leak alerts right to my phone. AO Smith’s app is good but can take longer to sync, especially with older smartphones.

Extra features matter when things go sideways—like when a leak hits. Rheem’s LeakGuard is built-in on many hybrid units and can shut off your water at the first sign of trouble. AO Smith leans on their self-cleaning dip tube (Signature series), which knocks down sediment before it gets out of hand. That means fewer flushes, less gunk, and fewer unwanted repairs.

For gas models, both brands offer high-efficiency condensing versions. Rheem’s Performance Platinum gas hits up to 0.80 UEF, while AO Smith ProLine XE Condensing is usually about 0.83. So if you run a big household, that matters—AO Smith eeks out a tad more efficiency for gas.

Bottom line: If you want all the digital bells and whistles, Rheem edges out AO Smith. If no-nonsense, reliable self-cleaning tech is your thing, AO Smith is a solid bet. Either way, shoot for a hybrid if you can. It’s more expensive at first, but the energy savings chew down your bills pretty quick.

Repair, Maintenance, and Warranty Insights

Here’s where things get real for anyone with an aging water heater. Both Rheem and AO Smith offer pretty accessible repair parts, but getting them fixed fast sometimes comes down to your installer and what your local hardware store carries. At most home improvement spots, you’ll find Rheem parts a bit more often, especially if you’re crunched for time. AO Smith isn’t rare, but some replacement components might need to be ordered in, causing an annoying wait.

When it comes to repairs, the most common call-outs for both brands are:

• Faulty thermostats
• Leaking tanks or valves
• Pilot light issues (for gas models)
• Sediment build-up
• Heating element failure (for electric models)

Some folks say that Rheem tanks can occasionally have finicky electronics, especially with their smart models, while AO Smith tanks get a bit of a bad rap for leaky valves on certain models. But honestly, both brands show up with these issues if maintenance slips.

Both brands recommend some simple steps for longer life:

• Drain the tank twice a year to flush out sediment
• Inspect the anode rod every two years; replace if it’s corroded
• Check all valves and connections for leaks at least once a year
• For gas models, keep the burner clean and check pilot operation

If you skip these, expect to call a repair tech sooner rather than later. Most of the time when I’m fixing a neighbor’s heater, it’s something that regular maintenance would’ve caught early.

Let’s talk warranty, because this is where money gets saved or lost. Here’s a quick breakdown:

Warranties are pretty evenly matched. Both give 6 years standard, and you can spring for extra coverage if you go for premium models. Labor usually only lasts the first 12 months, so after that, you’re on the hook for any service calls even if the part replacement is covered. It’s worth reading the fine print—some AO Smith models ship with a sticker on the tank saying you have to register within a set time to activate the Rheem warranty, so don’t skip that step.

If you have a tech install your water heater, keep the paperwork. DIY installations aren’t always covered, especially for warranty claims. I know a guy who lost his warranty just because he forgot to hang onto his Home Depot receipt. Don’t be that guy.

In the end, whether you go with Rheem or AO Smith, it’s the small habits—regular flushing, rod checks, fixing leaks—that keep the tank running and your warranty from going down the drain.