Gas vs Electric Water Heater
Updated 2026-08-15 · 6 min read
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The traditional comparison is gas versus electric resistance. That comparison still matters, but the more interesting question now is gas versus a heat pump water heater — because that changes the arithmetic entirely.
Is a gas or electric water heater cheaper to run?
Recovery rate
Gas burners deliver heat much faster than resistance elements. A gas heater refills its hot water supply considerably quicker, which is why a smaller gas tank often outperforms a larger electric one.
Compare first-hour rating, not gallons. See what size water heater do I need.
Running cost
Where gas is available, it's usually cheaper per unit of delivered heat than resistance electricity. Both convert their fuel to heat efficiently — the difference is the price of the input.
This flips in places with cheap electricity and expensive gas or propane. Run your own numbers rather than assuming — see cost to run a water heater and the electricity cost calculator.
Installation
Gas needs a gas line with adequate capacity and venting — either a flue to a chimney, or a power vent, or a direct vent through a wall. Combustion air requirements apply, and venting is where retrofit costs concentrate.
Electric needs a 240 V, 30 A circuit and no venting at all. Simpler, cheaper to install, and installable in more locations.
Power outages
An underrated difference.
- Standing-pilot gas: generally keeps working without electricity
- Electronic ignition or power vent gas: needs power, won't run
- Electric: needs power, won't run
If outage resilience matters to you, check which ignition type your gas heater has — many modern ones will not run in an outage, contrary to expectations.
Safety and maintenance
Gas involves combustion, which means carbon monoxide risk if venting fails. CO detectors are essential in any home with gas appliances, and venting should be inspected.
Electric has no combustion products and no venting to fail.
Is a heat pump water heater better than gas?
This is where the comparison changes.
A heat pump water heater uses electricity, but it moves heat rather than generating it — delivering roughly three to four units of heat per unit of electricity, versus one for resistance.
Consequently:
- Against electric resistance, it typically uses about a third of the energy
- Against gas, it often wins on running cost even where gas is inexpensive, because it's multiplying its input rather than burning it
The requirements are real though: enough air volume to extract heat from, a suitable ambient temperature range, a condensate drain, additional height, and some noise. See heat pump water heaters explained.
If you're on gas and considering switching, the questions are: do you have a basement or garage that suits one, do you have or can you get a 240 V circuit, and what are your local gas and electricity prices?
Side by side
| Gas | Electric resistance | Heat pump | |
|---|---|---|---|
| Efficiency | Good | ~100% (capped) | 300–400% |
| Recovery speed | Fast | Slow | Slowest (heat pump mode) |
| Running cost | Usually low | Highest | Usually lowest |
| Upfront cost | Moderate | Lowest | Highest |
| Venting | Required | None | None |
| Electrical | Minimal or none | 240 V / 30 A | 240 V / 30 A |
| Works in outage | Sometimes | No | No |
| Space needs | Standard | Standard | Extra height + air volume |
| Combustion safety | CO risk | None | None |
Can you switch a water heater from gas to electric?
Gas to electric needs a 240 V, 30 A circuit — a panel question. Check capacity and free positions before committing. The old gas line gets capped and the vent sealed. See can I add a breaker to my panel.
Electric to gas needs a gas line run and venting installed, which is usually the larger job. Rarely worth it purely for running cost unless the gas infrastructure is already close.
Either way, this is not a like-for-like swap, and the difference shows up in the installation quote. See water heater installation cost.
Should I buy a gas or electric water heater?
Gas makes sense when: you already have gas service and venting, you need fast recovery for heavy simultaneous demand, gas is cheap locally, or outage operation matters and you have a standing pilot.
Electric resistance makes sense when: there's no gas service, upfront cost is the binding constraint, or the location can't accommodate a heat pump model.
A heat pump water heater makes sense when: you have a basement or garage with adequate air volume, the ambient temperature stays in range, and you want the lowest running cost. In an all-electric home it's usually the clear answer.
Where to go next
More in our heating and cooling guides.
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