Tankless vs Tank Water Heaters for Metro Atlanta Homes

How do the two systems work?

A tank (storage) heater keeps a reservoir, usually 40 to 50 gallons, hot all the time. When you open a tap, hot water leaves the top and cold water refills the bottom. Because the tank sits hot even when nobody is home, it loses some heat through its walls, called standby loss.

A tankless (on-demand) heater has no reservoir. When a tap opens and water flows, a gas burner or electric element fires and heats the water as it passes through. It only runs when you need it, which is where the energy savings come from. The limit is flow: the DOE says tankless units typically deliver 2 to 5 gallons per minute, and gas models generally deliver more than electric.

How do they compare side by side?

HomeGuide's operating ranges overlap for gas units, which is a reminder that real savings depend on how much hot water your household uses. The DOE's figures make the same point more precisely, as the next section shows.

How much energy does tankless actually save?

According to the Department of Energy, a home that uses 41 gallons of hot water or less a day can expect a tankless heater to be 24 to 34 percent more energy efficient than a conventional storage heater. For a home using around 86 gallons a day, the gain drops to 8 to 14 percent. The DOE also notes that a gas tankless model with a standing pilot light can waste enough gas to cancel out much of its advantage, so look for models with intermittent (electronic) ignition.

In plain terms, a couple or small family that is careful with hot water sees the biggest percentage gain. A large household running long showers back to back still saves, but the savings take longer to cover the higher purchase price, and the payback period may approach the life of the unit.

Can one tankless unit keep up with your household?

This is the question that trips up most buyers. A tankless heater is sized by two numbers: how many gallons per minute you need at once, and how many degrees it must raise the water temperature.

• Flow: Add up the fixtures you might run at the same time. The DOE's sizing page uses about 2.5 gallons per minute for a shower and 0.75 for a hand faucet as examples, and suggests a unit that can handle at least 3.25 gallons per minute.
• Temperature rise: Subtract the incoming water temperature from the temperature you want. The DOE example assumes 50°F incoming water and 120°F at the tap, a 70°F rise, and says that rise is usually possible at about 5 gallons per minute for gas units but only about 2 for electric.

Incoming water in the Atlanta area is colder in January than in August, and a unit that keeps up easily in summer can struggle in a cold snap. Ask the installer to size for winter conditions. The DOE also warns that even large gas units can fall short when a shower and a dishwasher run together in a big household; the fix is a second unit or a dedicated unit for one high-use area.

For a tank, the matching number is the first hour rating on the EnergyGuide label: the gallons it can deliver in one busy hour. The DOE's example of three showers, one shave and a round of hand dishwashing adds up to 66 gallons, so that home needs a first hour rating of at least 66.

What does switching from tank to tankless involve?

Replacing a tank with another tank is usually a same-day swap. Converting to tankless is a bigger job, and HomeGuide's 2026 installation guide says it adds $600 to $2,500 in labor and typically takes half a day to a full day. Depending on the house, the conversion may also need:

• A larger gas line. Gas tankless units draw far more fuel at full fire than a tank burner. HomeGuide lists gas line upgrades at $350 to $2,000.
• New venting. Tankless gas units use dedicated venting that usually cannot reuse an old flue. HomeGuide puts new venting at $500 to $1,500.
• Electrical work for an electric tankless unit, which can need heavy-gauge circuits. HomeGuide lists a dedicated circuit at $250 to $900 and a panel replacement at $850 to $1,700.
• A permit and inspection. In the City of Atlanta, residential plumbing work goes through an online technical permit; Austell requires a plumbing permit for water heating equipment. Your installer should pull the permit for your jurisdiction.

These extras explain why two tankless quotes for the same house can be thousands of dollars apart. Ask each installer to itemize them. A plumber experienced with tankless water heater installation in Atlanta should be able to tell you on the first visit whether your gas meter and line are large enough.

Is natural gas available where you live?

Gas tankless units are the most common choice where gas service exists. Most of metro Atlanta gets gas through pipes run by Atlanta Gas Light, with the gas itself sold by a marketer you choose. A few cities run their own systems, among them Buford, Lawrenceville, Sugar Hill, Austell and Cartersville. If your home is all-electric, an electric tankless unit is possible, but the DOE's numbers show it delivers far less flow at the same temperature rise, so it suits a smaller household or a single bathroom better. A heat pump tank, which HomeGuide prices at $2,000 to $4,600 installed and $160 to $190 a year to run, is another option for all-electric homes.

Any change to gas piping is work for a qualified plumber or gas fitter. If you ever smell gas, leave the house first, then call 911 and your gas utility from outside; Atlanta Gas Light's emergency number is 877.427.4321, and your bill names the pipe utility if you are in a city-run system. Plumbers who handle gas piping for appliances can size the line for a new unit.

Does your water favor one type over the other?

Hard water leaves scale inside tankless heat exchangers and is the main reason they need descaling. Gwinnett County's Department of Water Resources lists its water at about 1.05 to 1.87 grains per gallon, which it calls soft, so homes in places like Duluth or Suwanee start with an advantage. Most other metro utilities do not publish hardness in their annual reports. Homes on private wells, more common at the edges of the region, should test before choosing tankless, since well water can carry more minerals.

Which should you choose?

Lean toward tankless if: you have natural gas, your household is small to midsize, you plan to stay in the home long enough to reach payback, and you want to free up floor space.

Lean toward a tank if: your current tank just failed and you need hot water today at the lowest installed cost, your family runs several showers at once, or the house would need a new gas line, venting and electrical work to convert.

Whichever way you go, get at least two itemized quotes and ask each installer how they sized the unit. If your current heater is failing and you are still deciding, our guide on whether to fix or replace a water heater helps with timing, and you can arrange a straight tank replacement if that is the better fit. Homeowners across the region, from Peachtree City to Gwinnett, can find more on our service area page.