Tankless vs. tank water heater: which actually saves you money?

Plumbing · 5 min read · By the OutToday team

Tankless water heaters have real advantages, but they aren't automatically the cheaper choice. Whether one saves you money depends on your home, and on a few costs that often get left off the quote.

What tankless does well

• Endless hot water: it heats water as you use it, so you don't run out mid-shower
• Lower energy use in many homes, because it isn't keeping 40 or 50 gallons hot around the clock
• A longer lifespan: tankless units commonly last 20 years or more, versus roughly 10 to 15 for a tank
• Space: a wall-mounted unit frees up a closet or corner of the garage

What tank water heaters do well

• Lower upfront price and simpler installation, especially when you're swapping like for like
• Simple, familiar technology that nearly every plumber can service
• Fewer surprises when the new unit fits the old location, connections, and venting

The cost most quotes forget

Converting from a tank to a tankless unit often means more than swapping the appliance. Ask whether the quote includes:

• Gas line upgrades. Tankless burners use more gas at once than a tank does, and an older, smaller gas line may need to be upsized.
• Venting. A tankless unit needs its own venting, and moving or replacing vent piping adds cost.
• A condensate drain for high-efficiency condensing models, and a nearby electrical outlet.
• The permit and inspection.
• Ongoing maintenance. Tankless units should be descaled periodically, especially where mineral buildup is a concern.

A quote that lists only the water heater and labor is missing part of the picture. Ask for the total installed price, in writing.

So which one saves money?

Tankless tends to win when you plan to stay in the home for years, use a lot of hot water, or are short on space, and when your gas line and venting are easy to work with. A tank tends to win when your budget is tight, the home is likely to change hands soon, or the conversion would require major gas and venting work.

The honest answer comes from looking at your actual setup. A technician can check your gas line, venting, and hot water demand and give you both options with real numbers.