Water heaters
Tank vs. Tankless Water Heater: Which Is Right for You?
Updated · By the Keystream Plumbing editorial team
How each one works
A tank heater keeps 30 to 80 gallons hot around the clock. A tankless heater heats water only when a tap opens, using a large gas burner or electric elements sized for flow rate.
Side by side
The main trade-offs:
- Upfront cost: tank is lower; tankless often needs gas line, venting or electrical upgrades
- Hot water supply: tank can run out; tankless supplies continuously up to its flow rate
- Lifespan: tank about 8 to 12 years; tankless 15 to 20 years with maintenance
- Space: tankless mounts on a wall
- Maintenance: both need flushing; tankless needs regular descaling in hard water
Climate matters
Tankless heaters must raise incoming water temperature by a set amount. In northern states, groundwater may be around 40°F in winter, so a unit that supplies two showers in Florida might only supply one in Minnesota. Size for your winter water temperature.
Heat pump water heaters
Heat pump models are tank heaters that move heat from the surrounding air, using far less electricity than standard electric tanks. They need space, airflow and a condensate drain, and they work best in garages and basements in warmer climates. Rebates are often available.
Getting it installed
Whichever you choose, installation should meet local code and usually needs a permit. See water heater replacement for what's involved.
Frequently asked questions
Do tankless water heaters really save money?
They reduce standby heat loss, typically lowering water heating energy use, but the higher install cost can take years to pay back. Savings are larger for gas households with modest hot water use.
Can a tankless heater run out of hot water?
It won't run out, but it can't exceed its flow rate. Too many fixtures at once makes water lukewarm.
Which lasts longer, tank or tankless?
Tankless heaters usually last longer, often 15 to 20 years, compared with about 8 to 12 for tanks.
Editorial note: This guide is general information for homeowners, not a substitute for an on-site assessment. Local codes and conditions vary; a licensed pro can confirm what applies to your home.
