We sell tankless. So you'd expect this page to say tankless wins every time. It doesn't. Tank water heaters are still the right answer for plenty of homes — short ownership timelines, tight budgets, simple installs. Tankless wins when you're staying long enough for the math to work, when space is at a premium, or when you genuinely need endless hot water. Here's the honest breakdown.
No marketing fluff. Real numbers, real tradeoffs, real recommendations either way.
Choose tankless if you'll own the home 8+ years, you want the space back from a 50-gallon tank, you regularly run out of hot water, or you're doing a major remodel anyway. Stay with a tank if you're moving in under 5 years, replacing on an emergency basis with no time for a complex install, working a tight budget, or your household demand fits comfortably in a 50-gallon tank. Tankless costs more upfront, lasts twice as long, uses less energy, and saves wall space — but only pays back over time.
The full picture, head to head.
Heats water as it flows · No storage
Heats and stores 30–80 gallons · Always ready
Most tankless vs. tank comparisons stop at the upfront price. That misses the most important variable: tank water heaters don't last as long. A typical tank lasts 10–12 years; a tankless lasts 20–25. So in a 25-year ownership window, you'll replace a tank twice while the tankless keeps going.
This shifts the math significantly. The tank's lower upfront cost gets neutralized by replacement and labor at the 12-year mark. By year 25, you've spent more on tank water heaters than on a single tankless — even before counting energy savings. That's the part people miss when they look at unit prices on Home Depot's website.
Storage tanks are a steel pressure vessel sitting in water 24/7. Even with a sacrificial anode rod (the magnesium or aluminum bar that corrodes instead of the tank lining), eventually the lining gives way and the tank starts leaking — which means a full replacement, not a repair. Tankless units have no large-volume water storage, no sacrificial anode to maintain, and individual components (heat exchanger, valves, sensors) can be replaced without scrapping the whole unit.
Here's the apples-to-apples math for a typical 4-person household over 20 years. Numbers are approximate and use national averages — your specifics will vary by climate, fuel cost, and install complexity.
| Cost Element | Gas Tank (50 gal) | Tankless (RTGH-95) |
|---|---|---|
| Initial unit cost | $700 | $1,400 |
| Initial install labor | $500 | $1,200 |
| Federal tax credit (25C) | $0 | −$600 |
| Year 0 net cost | $1,200 | $2,000 |
| Annual energy cost (gas) | $300/yr | $210/yr |
| 20 years of energy | $6,000 | $4,200 |
| Replacement at year 12 (unit + labor) | $1,400 | $0 |
| Annual descaling (hard water areas) | $0 | $2,000 ($100/yr) |
| 20-Year total cost of ownership | $8,600 | $8,200 |
| Tankless savings over 20 years | — | $400 |
The honest answer: over 20 years, tankless and tank cost roughly the same. The tankless premium gets recovered through energy savings, the avoided second purchase, and the federal tax credit. But the savings are modest — $400 over 20 years isn't life-changing. The real reasons to go tankless are the non-financial ones: endless hot water, reclaimed space, no flood risk, and a unit that won't fail in 12 years.
If you skip annual descaling (many people do, despite the manufacturer recommendation), tankless wins by roughly $2,000 over 20 years — but at the cost of a likely shorter tankless lifespan.
A lot of internet wisdom about tankless is half-true or outdated. Here are the ones we hear most:
More like 10–30%, and the high end requires a condensing unit, low daily usage, and a current tank that's old and inefficient. For an average household replacing a 5-year-old tank with a non-condensing tankless, the realistic savings are closer to 10–15%. Don't believe quotes higher than 30% without proof.
Tankless gives you endless hot water — not instant. There's typically a 10–30 second delay while the burner fires and water reaches the tap. If anything, the wait is slightly longer than a tank because the unit has to actually start. If "instant" matters, look at IKONIC models with built-in recirculation.
It lasts about 20–25 years with proper maintenance — twice a tank, but not forever. The heat exchanger has a 12 or 15-year warranty depending on the model; everything else is 1–5 years. In hard water areas without descaling, a tankless can fail much sooner.
You can — if you size the unit right. A properly sized RTG-84 or RTGH-95 handles two simultaneous showers in most US climates. The myth comes from undersized installs (often a low-end electric or a small gas unit picked on price) where the customer expected whole-home performance.
Tankless requires different maintenance than a tank, not less. Skip the annual descaling and your heat exchanger will scale up, efficiency will drop, and the unit will fail early. In hard-water regions (most of the US Midwest and Southwest), descaling is non-negotiable.
Sometimes true, sometimes not. If you're replacing an old 40-gallon tank with a 199K BTU tankless, yes — the gas line probably needs to be upgraded. If you're replacing a similarly-rated gas unit (or a new build), often no upgrade is needed. Get a contractor to assess your specific situation rather than assuming worst case.
Six common situations with our straight take.
Staying 10+ years, household regularly stresses the tank, want to escape the recovery time. The math works, the experience improves, the space comes back. Easy call.
Walls are open, plumbing is being redone anyway, you're already paying for permits. The marginal cost of going tankless is a fraction of the total project — and you get the lifespan and space benefits forever.
Tank failure means flooding a finished space. Tankless eliminates that catastrophic risk — no large volume of water to dump if the unit fails. For high-value finishes nearby, the insurance angle alone justifies it.
A new tankless adds maybe $500–$1,000 to a home sale, despite costing $2,000+ to install. The math doesn't work on a short ownership timeline. Replace the failed tank with a quality tank water heater and put the savings elsewhere.
Your tank just leaked at 6 PM and you need hot water by tomorrow morning. A tank replacement is same-day; a tankless install requires planning, possibly permits, and gas line evaluation. Don't make a 20-year decision under emergency time pressure.
If you've never run out of hot water, you don't need endless hot water. The energy savings are smaller for low-usage households (less standby loss to recover), and the install cost differential is harder to justify. A 30 or 40-gallon tank is genuinely fine.
Tell us about your home — bathroom count, climate, current water heater, how long you plan to stay — and we'll give you our honest take on whether tankless is worth it for you. Sometimes the answer is no, and we'll tell you that. Call 877-881-2742. RheemTanklessOnline.com is operated by LCP Supply alongside our flagship plumbing wholesaler PlumbersCrib.com — we sell both, so we can point you at the right answer.