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Tank vs Tankless Water Heater: 20-Year Cost Calculator

Compare total ownership cost, not just the install quote. Energy, yearly descaling, and the storage-tank replacement you will buy around year 12 are all in the math.

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Tank vs tankless: 20-year cost calculator

The install quote is only the first check you write. This compares total ownership cost: installation, yearly energy, maintenance, and the storage-tank replacement you will buy around year 12.

Planning ranges are not guaranteed quotes. Local labor and material conditions vary, and your install scenario moves the price more than any other factor.

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Common questions

How much does a tankless water heater save over 20 years?

It depends on fuel, usage, and your install scenario. For a typical gas home with medium hot water use, tankless saves roughly $400 to $1,700 over 20 years, mostly by using 25% less gas and avoiding a second tank purchase around year 12. Electric tankless rarely wins on cost alone because electric tanks are already efficient.

When does a tankless water heater break even?

In the model's typical gas scenarios, break-even lands around year 11 to 13, driven by the avoided tank replacement rather than energy savings alone. Simple energy-only payback looks shorter (8 to 10 years), but that math leaves out the $100 to $250 yearly descaling a tankless unit needs.

Does a tankless water heater really lower energy bills?

Yes, but modestly. DOE data shows 24 to 34% better efficiency at low to medium hot water use, which ENERGY STAR translates to about $95 a year for a family of four on gas. At high simultaneous demand the advantage shrinks to 8 to 14%.

What maintenance does a tankless water heater need?

Annual descaling to prevent mineral buildup, typically $100 to $250 per professional service. Skip it and efficiency drops, error codes appear, and the 20-year lifespan shortens. A storage tank needs far less: periodic flushing and an anode rod every few years.

When is a regular tank water heater the better choice?

When you plan to sell within about 10 years, when the conversion quote lands at the top of the range, or when your household barely uses hot water. In those cases the install premium never pays back, and another tank is the rational call.