Tank vs. Tankless Water Heater: Which Is Right for Your Home?

The core difference

A tank water heater stores and continuously reheats a set volume of hot water — typically 40-50 gallons for a household. A tankless unit heats water on demand as it flows through, with no storage at all. That single difference drives almost every other tradeoff between the two.

Where tank units win

Lower upfront installation cost, since most homes already have the gas line size, venting and electrical setup a tank needs. Simpler repairs with widely available parts. No risk of running short on hot water during simultaneous heavy use, since a full tank is already heated and waiting, within its capacity.

Where tankless units win

Continuous hot water with no risk of running out, as long as usage stays within the unit's flow rate. Lower standby energy loss, since there's no tank of water being kept hot around the clock. A much smaller footprint, which matters in tight mechanical closets common in older homes. Longer typical lifespan when properly maintained.

What a tankless conversion actually requires

This is the part that changes the cost comparison: tankless units draw significantly more gas instantaneously than a tank, which often means upsizing the gas line. They also typically need different venting than a tank did. In hard water areas, adding a scale-inhibiting filter protects the heat exchanger and is worth budgeting for. See our tankless installation page for the full breakdown of what a conversion involves.

A reasonable way to decide

If your household regularly runs out of hot water, you're renovating and want the floor space back, or you're planning to stay in the home long enough to recoup the higher upfront cost through lower operating cost, tankless is worth a serious look. If your current tank works fine and you're simply replacing it at end of life without any of those pressures, a new tank is usually the lower-friction, lower-cost choice.