In short
HomeAdvisor’s tankless guide, updated June 17, 2026, lists professional installation at $1,406–$3,902, average about $2,641, and a wider possible span of $384–$6,000. Fuel, whole-house versus one fixture, and permits move the job. The tank-replacement table on the other page is a different guide. Neither number is a Sabino Creek quote. Checked October 19, 2026.
What changes when you leave the tank behind
A tank keeps a reservoir hot. A tankless unit fires when a faucet opens and stops when it closes. HomeAdvisor says that difference is why standby loss drops, and it says tankless units can be 24% to 34% more energy efficient for homes using up to 41 gallons of hot water a day. That efficiency sentence is theirs. It is not a Tucson bill we calculated, and it is not a promise that your electric or gas account will fall by that share.
The same guide says a tankless unit lasts around 20 years with maintenance, against 8–12 years for a conventional tank. The replacement guide on water heater replacement says tank-style life is 6–15 years. The two HomeAdvisor pages do not use one lifespan. Quote the page you are reading, and let the contractor judge the unit that is actually in the closet.
Installed cost by fuel
These ranges are “average cost with installation” on HomeAdvisor’s tankless cost guide, updated June 17, 2026. The headline range above is the project range. The fuel table is a narrower cut. Do not treat a $1,000 gas row as a contradiction of the $2,641 average. HomeAdvisor published both.
| Fuel | HomeAdvisor average cost with installation |
|---|---|
| Natural gas | $1,000–$1,500 |
| Propane | $1,000–$1,500 |
| Electric | $450–$1,500 |
| Solar | $1,800–$6,000 |
HomeAdvisor also says a small single-point electric model can cost as little as $100 for the unit, a typical natural-gas unit about $1,000–$1,500, and solar whole-house units $1,700 or more before you are in the installed solar row. Point-of-use heaters, sitting at one sink or shower, are listed at $100–$250. Whole-house units are discussed around $450–$1,500 for the equipment conversation on that page, separate from the $1,406–$3,902 installed project range. If a quote is only the box, ask whether venting, gas piping, and electrical work are in it.
Flow rate is the size
There is no gallon tank to point at. HomeAdvisor sizes these by gallons per minute. A point-of-use unit is described at 1–2 GPM. A larger whole-house unit is described at 5–10 GPM. Their fixture list: a faucet 1–2 GPM, a dishwasher 1.5–2, a washing machine 2–2.5, a low-flow shower 2–3, a conventional shower 4–6. Add the fixtures that actually run together. Two showers at once are two showers, not one. HomeAdvisor notes that electric models on that page top out around 8 GPM, while some gas models go higher, including a mention of 20 GPM.
The guide quotes a reviewer, Cati O’Keefe, that an electric whole-house tankless heater needs 240-volt, 80-amp service at a minimum, and that the house needs at least 150-amp service to run the other appliances with it. That is a panel question. It is the same kind of question a heat-pump install raises, and it is why an electric tankless quote can grow after the panel is seen. We do not size panels from the form.
Permits, access, and brands
The guide’s overview says building permits of $150–$500. The body says permits can run $50–$500, and that some places treat a replacement differently from a new installation. Both sentences are on the same page. Neither is a Tucson fee. Access that is cramped is listed as adding about 10% to 15% of labor. Brand unit ranges on that page run from EcoSmart at $150–$1,600 through Takagi at $900–$3,000. Those are unit prices in HomeAdvisor’s brand table, not installed Tucson bids.
Hard water and the setpoint
HomeAdvisor says to set the heater at 120°F and attributes that to the U.S. Consumer Product Safety Commission, for scalding and for energy use. The same answer says temperatures above 140°F raise burn risk and promote mineral buildup. ContractorBear says Tucson water averages 12–18 grains per gallon. Scale in a heat exchanger is a known hard-water problem. We are not claiming a flush interval, because neither source gives one we are willing to repeat as a Tucson rule. If the question is a softener rather than the heater, that is hard water and water softeners.
Gas models still need electricity for ignition and controls. HomeAdvisor says they do not heat during an outage unless a battery backup or a generator is installed. A gas unit is also a combustion appliance. Venting and carbon monoxide belong to the contractor and, if an alarm sounds, to 911. Read carbon monoxide safety before you treat a smell as a form question.
Source
HomeAdvisor, “How Much Does a Tankless Water Heater Cost,” updated June 17, 2026: homeadvisor.com/cost/plumbing/install-a-tankless-water-heater. The tank table lives on the replacement page so the two ranges are not blended.