The big picture:

Water heating runs all year. That makes it the load where the gap between a good unit and a cheap one is widest. The U.S. Energy Information Administration (EIA) groups water heating, lighting and cooling at 25% of home energy use in 2020. Heating and air conditioning take the other 52% [9].

So the tank is a smaller slice of the bill than most owners assume. It also holds a much larger share of the waste an owner can fix, because a cheap unit wastes fuel for its whole service life while the purchase price is paid once.

The federal floors are where that gap shows up. A gas tank of 20 to 55 gallons, built before May 6, 2029, must score 0.6483 minus 0.0017 times its rated gallons. At 50 gallons that is 0.5633 [3]. A standard electric tank in the same range must score 0.9307 minus 0.0002 times gallons, or 0.9207 at 50 gallons [4]. Those scores measure how much heat a unit gets from the fuel it takes in, so a higher number is better.

From May 6, 2029 the electric floor jumps to 2.30 for every usage pattern. Plain heating elements cannot reach that [5]. The date that matters is when the unit is built, not when it is sold or installed.

50-gallon, mid-draw floor Score Cost per million Btu
Standard electric, today 0.9207 $55.07
Gas-fired, today 0.5633 $26.26
Electric from May 2029 2.30 $22.04

The three rows are the classes a homeowner will be offered at a 50-gallon size. Mid-draw means a medium amount of daily use, which is how most households run a tank. My read is that this is the rare energy choice where the physics beats the sales pitch. The pitch is also where the money leaks. A tank replacement comes once a decade, and it is the same moment the big gas units’ venting trap already described.

By the numbers

  • $26.26 — Gas tank, per million Btu: 2025 gas at $15.34 a thousand cubic feet comes to $14.79 a million Btu of fuel. Divide that by the 0.5633 floor and the hot water costs $26.26 [1][3][7]. That division is the desk’s own.
  • $22.04 — Heat pump tank, per million Btu: power at 17.30 cents a kilowatt hour comes to $50.70 a million Btu. Divide that by the 2.30 floor that applies to units built from May 2029 and the hot water costs $22.04 [2][5][6]. A heat pump moves heat rather than burning fuel to make it.
  • $55.07 — Standard electric tank, per million Btu: the same power divided by today’s 0.9207 floor for a 50-gallon unit. That is 2.10 times the gas tank’s cost [2][4][6].
  • 20.6 cents — The break-even price: heat pump and gas cost the same when home power reaches about 20.6 cents a kilowatt hour at $15.34 gas. Below about $12.88 a thousand cubic feet, gas wins [1][2][3][5][7].

What I’d watch:

The quote is where the class gets chosen. Its wording shows which comparison the seller is making.

  • The score line: a quote that reads “50-gallon gas, same as yours” is selling a class, and every class has a number on it. What I would want to see is that score printed beside the model. The legal floor and the unit on the shelf are rarely the same figure [3].
  • The room a heat pump needs: it wants 1,000 cubic feet of air in a space that stays between 40 and 90 degrees all year. The program warns that colder spots cut efficiency and can force a standard electric backup [8]. A closet or a cold garage corner is the usual block. That is a fact about the house rather than about the box.
  • The local power rate: the 20.6-cent break-even moves with a household’s own rate. A home well above the national average gets a different answer from the same two floors [2][5].
  • The 2029 repair clock: a standard electric tank fitted in 2026 is the last of its class to be built new. That matters when the same owner weighs a repair against a new unit before that date [5].

The catch

The honest limit is that the gap is narrow. The heat pump tank at the 2029 floor beats the gas tank by about 16%. Cheap gas takes that lead back on any day when it is priced close to power [1][2][3][5]. I could be wrong about how heavily a home should weigh that margin. No figure here includes a fitted price, and without one there is no payback in dollars to quote.

What the numbers do settle is the class to refuse. A standard electric tank at 0.9207 costs 2.10 times the gas tank for every million Btu of heat [2][4][6]. Nothing in this price set closes that gap. The part I keep circling is that the same tank is the cheapest box on the shelf, which is why it keeps going into houses that will carry the bill for ten years.

At a glance

  • The Big Shift: The class a water heater must meet sets the bill far more than the fuel it burns. That gap widens on May 6, 2029, when new electric tanks must reach a score of 2.30, which is heat pump territory.
  • Why It Matters: At 2025 prices the same million Btu of hot water costs about $26.26 from a 50-gallon gas tank, $22.04 from a heat pump tank at the 2029 floor and $55.07 from a standard electric tank. The class chosen at replacement sets ten years of bills.
  • What I’d Watch: Two published prices and two legal floors now decide the answer. The state spread is where it moves.
  • The break-even price: the power rate where heat pump and gas cost the same, about 20.6 cents a kilowatt hour at 2025 gas prices.
  • The room it needs: the 1,000 cubic feet of air and the 40-to-90-degree range a heat pump needs to run at its rating.
  • The May 2029 floor: the date the electric class must reach 2.30, which ends the standard electric tank as a new option.
  • The Catch: The heat pump’s edge is roughly 16% per million Btu of heat, not the halving that sales talk implies. No fitted price appears in these figures, so there is no dollar payback to promise.

Related reading

Sources

[1] U.S. Energy Information Administration, “U.S. Price of Natural Gas Delivered to Residential Consumers” (annual series, release 2026-09-30) — https://www.eia.gov/dnav/ng/hist/n3010us3A.htm [2] U.S. Energy Information Administration, “Prices and factors affecting electricity prices” (2025 annual averages) — https://www.eia.gov/energyexplained/electricity/prices-and-factors-affecting-prices.php [3] 10 CFR 430.32(d)(1), gas-fired storage water heater efficiency floor, units made before May 6, 2029 — https://www.ecfr.gov/current/title-10/chapter-II/subchapter-D/part-430/subpart-C/section-430.32 [4] 10 CFR 430.32(d)(1), electric storage water heater floor, units made before May 6, 2029 — https://www.ecfr.gov/current/title-10/chapter-II/subchapter-D/part-430/subpart-C/section-430.32 [5] 10 CFR 430.32(d)(2), electric storage water heater floor for units made on or after May 6, 2029 — https://www.ecfr.gov/current/title-10/chapter-II/subchapter-D/part-430/subpart-C/section-430.32 [6] U.S. Energy Information Administration, “Units and calculators explained” (Btu conversion factors) — https://www.eia.gov/energyexplained/units-and-calculators/ [7] U.S. Energy Information Administration, FAQ on converting gas prices to dollars per million Btu (2025 heat content) — https://www.eia.gov/tools/faqs/faq.php?id=45&t=8 [8] ENERGY STAR, “Heat Pump Water Heaters” (setup guidance) — https://www.energystar.gov/products/heat_pump_water_heaters [9] U.S. Energy Information Administration, “Use of energy in homes” (2020 end use shares) — https://www.eia.gov/energyexplained/use-of-energy/homes.php