A gas water heater reheats faster, so a smaller tank covers the same demand, and it is usually cheaper to run where natural gas is inexpensive. An electric tank is simpler and cheaper to install, needs no vent and has no combustion risk, but recovers slowly and costs more to run in most provinces. A heat pump water heater is electric but can match or beat gas on running cost, depending on your rates.
- Gas burners add heat faster than electric elements: a typical 40-gallon gas tank delivers about 260 L in its first hour, a 40-gallon electric tank about 200 L.
- Running cost depends on your prices: at $8/GJ and 20¢/kWh a gas tank costs about $170 a year for three people and an electric tank about $797.
- Gas needs a gas line, a vent, a permit and a licensed gas fitter, plus carbon monoxide alarms; electric needs a 240 V circuit.
- Many atmospheric gas tanks keep heating in a power outage; electric, power-vent and heat pump units do not.
- A heat pump water heater narrows or reverses the running-cost gap for electric homes.
01 /Is a gas or electric water heater better?
Neither is better everywhere. Gas wins on recovery speed and, in most of Canada, on running cost. Electric wins on installation simplicity, placement flexibility and safety, because nothing burns. The right answer for a given house depends on four things: whether gas is already there, how the heater can vent, your energy prices, and how much hot water your household uses in its busiest hour.
02 /Why does a gas tank recover faster?
A gas burner simply delivers more heat per hour than a household electric element. A common electric element is 4.5 kW. Heating water by 42 degrees takes 4.186 kJ per litre per degree, so a 4.5 kW element reheats about 92 litres an hour (4.5 × 3,600 ÷ (4.186 × 42)). A typical residential gas burner rated around 40,000 BTU/h has about 11.7 kW of input; even if only about three-quarters of that reaches the water, it reheats roughly 180 litres an hour, nearly twice as much.
That is why the size tables differ. In the typical ratings used by the Water Heater Size Calculator, a 50-gallon gas tank delivers about 310 litres in its first hour, while an electric tank needs to be about 65 gallons to deliver about 270. A household that runs four showers, a bath and a load of laundry in one hour (about 269 litres) needs a 50-gallon gas tank or a 65-gallon electric one. Electric tanks compensate with size; that costs floor space and standby losses.
03 /Which is cheaper to run?
It depends on the price you pay for each unit of heat and on each heater's efficiency. Gas is sold by the gigajoule (GJ) and electricity by the kilowatt-hour; one GJ equals 277.8 kWh. At 20¢/kWh, a GJ of electricity costs $55.56. If gas costs $8 per GJ, electricity is about seven times dearer per unit of energy, and the electric tank's higher efficiency (0.92 against 0.62) closes only part of the gap.
| Heater | At $8/GJ gas and 20¢/kWh | At $14/GJ gas and 9¢/kWh |
|---|---|---|
| Gas tank (0.62) | ~$170 | ~$298 |
| Power vent (0.66) | ~$160 | ~$280 |
| Electric tank (0.92) | ~$797 | ~$359 |
| Heat pump (3.0) | ~$244 | ~$110 |
The second column shows why the answer changes by region. Where gas is dearer and electricity cheaper, an ordinary electric tank comes within about $60 a year of a gas tank, and a heat pump becomes the cheapest to run by a wide margin. Run your own numbers in the Energy Cost Comparer, and see the Across Canada page for regional patterns. Water heating is a big line item either way: Natural Resources Canada puts it at 19.3% of an average Canadian household's energy use.
04 /What does installation involve for each?
Gas. A gas water heater needs a gas supply sized for its input, a shut-off valve and sediment trap at the appliance, a vent path, combustion air, a permit and a licensed gas fitter. Rules on who may do gas work are set provincially. In Calgary, for example, the City states that a homeowner can apply for a gas permit only if they are an Alberta certified journeyman gasfitter; in Ontario, TSSA says only registered fuels contractors may legally do fuels work; British Columbia allows homeowner gas permits for eligible homeowners, including water heater replacement. See permits and code.
Electric. An electric tank needs a dedicated 240 V circuit of the size the manufacturer specifies, plus the same plumbing as any tank: shut-off valve, T&P discharge pipe, and an expansion tank where the system is closed. Electrical work falls under provincial and municipal electrical permit rules.
Switching fuel. Going from gas to electric may need a new circuit and, in older homes, a check of panel capacity. Going from electric to gas needs a gas line and a vent path, which can cost more than the heater. Going from a gas tank to a heat pump usually needs a 240 V circuit, a condensate drain and enough space and air around the unit. The installation guide and cost guide cover these.
05 /Which is safer?
Both are safe when installed and maintained correctly, but the risks differ. A gas water heater burns fuel, so it can produce carbon monoxide if venting fails or exhaust spills back into the house. Health Canada advises installing certified CO alarms if you have fuel-burning appliances, with hallways outside sleeping areas the most important location, and having those appliances inspected at least once a year or as the manufacturer directs. Stored paint, solvents and gasoline should never be near a gas water heater's burner.
An electric tank has no combustion risk, but it runs on 240 volts. Never remove element covers without switching off the breaker, and treat any leak near its wiring as an electrical hazard. Both types share the same scald and pressure risks: store at 60 °C to limit Legionella and use mixing valves to deliver about 49 °C at the tap, and keep the T&P valve and its discharge pipe unobstructed.
06 /What happens in a power outage?
An atmospheric gas tank with a standing pilot and a thermopile-powered gas control needs no electricity, so it keeps heating during an outage, which is useful in a Canadian ice storm. Tanks with electronic ignition, power-vent tanks and most gas tankless units need electricity and stop. Electric and heat pump tanks stop too, though a well-insulated full tank stays usefully warm for some hours. If outage resilience matters, check the control type on the rating plate or manual before you buy.
07 /Where does a heat pump water heater fit?
A heat pump water heater is electric, but it changes the economics. Natural Resources Canada says ENERGY STAR certified models use up to 70% less energy, on average, than a standard electric water heater. In the first price example above, that takes the electric running cost from about $797 to about $244 a year. It needs a 240 V circuit, a condensate drain, space and air around it, and it cools the room it sits in. For an electric home without gas, it is usually the running-cost upgrade to consider first.
Read heat pump water heaters for placement and cold-basement performance, and tankless vs tank if on-demand gas is on your list.
08 /A quick decision guide
| Your situation | Lean toward |
|---|---|
| Gas in the house, sound chimney, cheap gas | Atmospheric or power-vent gas tank |
| Gas in the house, chimney orphaned or gone | Power-vent, direct-vent or condensing gas; or heat pump |
| No gas, basement with space and a drain | Heat pump water heater |
| No gas, tight space, low use | Electric tank |
| Cheap electricity, dear gas | Heat pump, or electric tank if the heat pump does not fit |
| Outage resilience matters | Atmospheric gas with a standing pilot |
Size the option with the size calculator, compare the running costs with your own prices, and read the types of water heaters guide for the full list. HotWaterTank.ca is independent and does not recommend brands. When you are ready, you can request quotes.
FAQQuestions people ask
Is a gas or electric water heater cheaper to run?
In most of Canada gas is cheaper per unit of heat, so a gas tank usually costs less to run. Where gas is expensive and electricity cheap, the gap narrows, and a heat pump water heater can be cheapest. Use your own rates.
Is my hot water tank gas or electric?
Look for a vent pipe on top and a gas line with a valve at the bottom: that is gas. An electric tank has no vent, a thick electrical cable into a box on top, and two small covers on the side for the elements.
Does an electric water heater use a lot of electricity?
Yes, relative to most appliances. For three people using 180 litres a day, a standard electric tank uses about 4,000 kWh a year; a heat pump model about 1,200 kWh.
Do gas water heaters work without power?
Many atmospheric tanks with a standing pilot and thermopile control do. Power-vent, electronic-ignition and most tankless models need electricity.
Is a hot water heater 110 or 220 volts?
Standard electric tanks in Canada run on 240 V. Power-vent gas tanks use a standard 120 V outlet for the fan. Heat pump tanks usually need 240 V.
Can I switch from gas to electric?
Yes, with a suitable 240 V circuit and panel capacity. Have the gas line capped by a licensed gas fitter and consider a heat pump model to limit running costs.