When it comes time to replace a water heater, you’ll quickly notice the same three names popping up: State ProLine, AO Smith, and Rheem. These brands dominate the residential water heater market, especially in the popular 40-gallon size—the sweet spot for many families of 2–4 people.
But which one is right for you?
I’ve lived with and worked on all three. My neighbors swear by Rheem, my cousin won’t use anything but AO Smith, and I’ve had solid luck with the State ProLine in my own home.
So, in this guide, I’ll compare performance, cost, warranty, efficiency, and maintenance across these brands, and share my honest opinion on which one I’d recommend for most households.
🏠 Brand Backgrounds
🔵 State ProLine
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A subsidiary of AO Smith, but with its own distinct product lines.
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Known for durable gas water heaters that are straightforward to install and maintain.
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Focuses heavily on reliability for everyday homeowners rather than cutting-edge tech.
👉 My take: State is the “workhorse” brand—no frills, but dependable.
🟢 AO Smith
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One of the biggest names in water heating, in business since 1874.
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Offers a wide range: tank, tankless, hybrid, and commercial units.
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Strong reputation for innovation, including hybrid electric and high-efficiency gas models.
👉 My take: AO Smith is the brand you choose if you want options and are willing to pay for premium features.
🟠 Rheem
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Founded in the 1920s, Rheem is a global leader in heating, cooling, and water heating.
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Known for energy-efficient products, with many ENERGY STAR-certified models.
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Offers strong customer support and one of the broadest service networks.
👉 My take: Rheem is the efficiency-focused brand—great if energy savings is top priority.
🔗 Rheem Official Site – Residential Water Heaters
⚡ Performance Comparison (40-Gallon Gas Models)
Let’s start with what matters most: can these heaters keep up with daily household demand?
| Feature | State ProLine 40-Gal | AO Smith 40-Gal | Rheem 40-Gal |
|---|---|---|---|
| First Hour Rating (FHR) | 65–70 gallons | 67–72 gallons | 65–71 gallons |
| Recovery Rate | ~40 GPH (at 40,000 BTU) | ~40 GPH (at 40,000 BTU) | ~40 GPH (at 40,000 BTU) |
| Peak Suitability | Families of 2–3, light 4 | Families of 3–4 | Families of 3–4 with high usage |
👉 Mike’s Note: On pure heating performance, these three are almost neck-and-neck. A 40-gallon gas tank will comfortably handle 2–3 people in most cases, but with teenagers or back-to-back showers, you’ll notice limits.
🔗 Energy.gov – Sizing Water Heaters
💰 Cost & Value Breakdown
The purchase price and installation cost often sway homeowners more than brand loyalty. Here’s what I’ve seen in real-world pricing:
| Brand | Unit Price (40-Gal Gas) | Installed Price (Pro Labor) | Value Rating |
|---|---|---|---|
| State ProLine | $600–$850 | $1,200–$1,600 | ⭐⭐⭐⭐⭐ (Great balance) |
| AO Smith | $700–$1,000 | $1,300–$1,800 | ⭐⭐⭐⭐ (Premium priced) |
| Rheem | $750–$1,100 | $1,400–$1,900 | ⭐⭐⭐⭐ (Paying for efficiency) |
👉 Mike’s Take: State ProLine is usually the most affordable upfront. AO Smith and Rheem tack on extra cost, but they often include longer warranties or efficiency features that can pay off over time.
🔗 Forbes – Water Heater Installation Costs
📜 Warranty & Reliability
A water heater is only as good as its longevity.
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State ProLine: 6-year limited warranty standard. Solid tank design, fewer electronics = fewer points of failure.
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AO Smith: 6–10-year warranties depending on model tier. Premium models push coverage further.
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Rheem: 6 years standard, with 9–12 years on ENERGY STAR and high-end units.
👉 My experience: State tanks last 10–12 years with proper maintenance. AO Smith and Rheem can stretch longer, but only if you pay for higher-tier models.
🔗 How Long Do Water Heaters Last?
🌱 Energy Efficiency & Operating Costs
This is where differences start to show:
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State ProLine: Solid performers, but not always ENERGY STAR certified in 40-gallon gas models. Good for households that prioritize upfront cost over maximum efficiency.
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AO Smith: Offers high-efficiency gas and hybrid options. If you want to cut utility bills long-term, AO Smith has strong contenders.
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Rheem: Aggressively markets ENERGY STAR-certified models. Efficiency ratings are slightly higher on average than State or AO Smith in the same class.
👉 Mike’s Tip: Don’t just look at the sticker price. Over 10 years, energy savings from an efficient model can easily offset $200–$300 in upfront cost.
🔗 ENERGY STAR – Water Heater Product Criteria
🛠️ Maintenance & Service
This is where my personal experience really comes into play.
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State ProLine: Straightforward design = easier for DIY maintenance. Flushing sediment, replacing anode rods, and cleaning burners is simple.
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AO Smith: Good manuals and support, but some models use proprietary parts that cost more.
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Rheem: Fantastic service network and replacement part availability. But, higher-efficiency models have more electronics, which means more things to break.
👉 My experience: If you’re the kind of homeowner who likes to do your own flushing and anode rod replacements, you’ll appreciate State’s simpler design.
🔗 Family Handyman – How to Replace a Water Heater Anode Rod
🧾 Pros & Cons Summary
🔵 State ProLine
Pros: Affordable, reliable, simple maintenance.
Cons: Fewer high-efficiency models, shorter warranty.
🟢 AO Smith
Pros: Wide variety, advanced options, extended warranties available.
Cons: Pricier, parts can cost more.
🟠 Rheem
Pros: High efficiency, ENERGY STAR options, excellent service network.
Cons: Higher upfront cost, more complex models.
✅ Mike’s Final Recommendation
So, after looking at cost, performance, efficiency, and reliability, here’s my verdict:
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Choose State ProLine if you want a reliable, budget-friendly, no-nonsense water heater that just works. It’s the best bang for your buck in the 40-gallon category.
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Choose AO Smith if you’re after premium features, extended warranty coverage, or hybrid models. It’s the upscale choice.
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Choose Rheem if you want the most efficient option and don’t mind paying more upfront for long-term savings.
👉 For most families (mine included), I recommend the State ProLine 40-Gallon Gas Water Heater. It balances cost, reliability, and performance better than the competition, and it’s easier to maintain without calling a plumber for every little thing.
In the end, the best water heater is the one that matches your household size, budget, and comfort priorities—but if you asked me to pick today, I’d stick with State.
In the next topic we will know more about: Do Gas Water Heaters Qualify for Rebates or Tax Credits in 2025? Mike Breaks It Down
