Tankless vs Tank Water Heater: What Ontario Homeowners Actually Pay

The tank vs tankless water heater question comes up every time a water heater dies or a homeowner gets tired of the rental company taking $60+ per month off the top. Both options work. Neither is universally better. The right choice depends on your household size, hot water usage, and whether you are looking at 5-year costs or 15-year costs.

What Each Type Costs to Buy and Install

Tank Water Heater: $1,200 - $2,800 Installed

A standard tank water heater stores 40 to 60 gallons of hot water and keeps it hot around the clock. Gas models are more common in Ontario homes with existing gas lines. Electric models are simpler to install but cost more to operate.

40-gallon gas tank: $500-$900 for the unit, $700-$1,200 for installation. Total: $1,200-$2,100.
50-gallon gas tank: $600-$1,000 for the unit, $700-$1,200 for installation. Total: $1,300-$2,200.
60-gallon gas tank (large family): $800-$1,300 for the unit, $800-$1,500 for installation. Total: $1,600-$2,800.
Electric tank (40-50 gallon): $400-$800 for the unit, $500-$900 for installation. Total: $900-$1,700.

Installation is straightforward if you are replacing like-for-like. The old unit comes out, the new one goes in the same spot, connects to the same water lines and gas/electric supply. If you are changing fuel type (gas to electric or vice versa), add $500-$1,500 for the additional electrical or gas work.

Tankless Water Heater: $3,900 - $6,500 Installed

A tankless water heater heats water on demand as it flows through the unit. No storage tank, no standby heat loss. They are compact, wall-mounted, and last roughly twice as long as tank models.

Gas tankless (whole-home): $1,800-$3,000 for the unit, $2,100-$3,500 for installation. Total: $3,900-$6,500.
Electric tankless (point-of-use): $300-$700 for the unit, $300-$600 for installation. Total: $600-$1,300. Note: electric tankless units for whole-home use require very high amperage (150-200 amps) and are rarely practical in Ontario homes with 100-200 amp panels.

The installation cost for gas tankless is significantly higher than tank because the work involves more than just a swap. A typical gas tankless installation requires:

Upgrading the gas line to 3/4-inch or larger (tankless units have higher BTU demands)
Installing stainless steel venting (cannot use standard B-vent like a tank)
Adding a condensate drain line (condensing tankless models produce acidic condensate)
Electrical connection for the control board
Removing and disposing of the old tank

Monthly Operating Costs

This is where the long-term math matters. Using 2026 Ontario rates:

Gas Tank Water Heater

A standard gas tank water heater uses about 200-250 cubic metres of gas per year for a family of four. At $0.30/m3 all-in, that is $60-$75 per month in operating cost. Some of that energy is wasted keeping 50 gallons of water hot 24/7, including the 8+ hours per day nobody uses any hot water.

Gas Tankless Water Heater

A tankless unit only fires when you open a hot water tap. No standby losses. Typical gas consumption is 30-40% lower than a tank for the same household. That brings operating cost down to $35-$50 per month for a family of four.

The monthly savings are $20-$30 per month, or $240-$360 per year. Over the 20+ year lifespan of a tankless unit, that adds up to $4,800-$7,200 in energy savings — which more than offsets the higher purchase and installation cost.

The Rental Trap

Many Ontario homeowners rent their water heater from companies like Enercare, Reliance, or their utility provider. Monthly rental fees in 2026 range from $25 to $65+ per month depending on the equipment. Over 10 years, that is $3,000-$7,800 — and you never own the equipment. When you sell your home, the rental contract transfers to the buyer, which some buyers push back on during negotiations.

Buying your water heater (tank or tankless) almost always saves money over a 10-year period compared to renting. The breakeven point on a purchased tank is typically 3-5 years. For tankless, it is 5-7 years when you factor in the higher upfront cost.

Lifespan and Maintenance

Tank water heater: 10-12 years average lifespan. Maintenance is minimal — flush the tank annually and replace the anode rod every 3-5 years. Most people skip both and the tank lasts 8-10 years instead.
Tankless water heater: 20-25 years average lifespan. Requires annual descaling (flushing with vinegar solution) to prevent mineral buildup, especially in areas with hard water. A maintenance flush costs $150-$250 if you hire a plumber, or about $30 in vinegar and an hour of your time if you do it yourself.

When Tankless Does NOT Make Sense

Tankless is not always the better choice. Skip it if:

Small Household (1-2 People)

If you live alone or with one other person, your hot water usage is low. A 40-gallon tank will handle your needs without running out, and the energy savings from tankless will not be enough to justify the higher upfront cost within a reasonable timeframe. A tank will cost $1,200-$1,800 installed and last 10+ years. Hard to beat that math.

Hard Water Area Without a Softener

Many parts of Mississauga, Brampton, and the 905 region have hard water (high mineral content). Tankless heaters are more susceptible to mineral scale buildup than tank models. Without a water softener, a tankless unit in a hard water area will need more frequent flushing and may have a shorter lifespan. If you are not willing to install a softener or commit to regular maintenance, a tank is the safer bet.

Budget Is the Priority

If you need hot water tomorrow and your budget is $2,000, a tank is your only realistic option. A good 50-gallon gas tank installed by a licensed plumber will serve you well for the next decade. No shame in that choice.

Very High Simultaneous Demand

Tankless units have a maximum flow rate. A standard residential gas tankless can deliver about 7-9 gallons per minute of hot water. If you have a household that regularly runs two showers, a dishwasher, and a washing machine simultaneously, a single tankless unit may not keep up. You would need two units or a high-capacity commercial model, which pushes the cost past $8,000.

When Tankless Makes Great Sense

Family of 3-5 people: Higher usage means faster payback on the energy savings.
Home with limited space: Tankless units are small and wall-mounted. They free up the floor space a tank occupies.
Planning to stay long-term: If you will be in the home for 10+ years, the lifetime cost of tankless is lower than tank.
Replacing a rental: If you are paying $50+/month to rent a tank, a purchased tankless unit pays for itself faster.
Renovating anyway: If you are already opening up walls for a renovation, the incremental cost of tankless installation drops because the gas line and venting work is easier with open access.

Get the Right Water Heater for Your Home

Relica Comforts installs both tank and tankless water heaters and we will give you an honest recommendation based on your household, not a sales pitch. Our licensed plumbers handle the full job — removal of the old unit, gas line work, venting, permits, and testing. Water heater installation across the GTA to Barrie, with written quotes and no hidden fees.

Serving Mississauga, Brampton, and all GTA communities. Call (647) 491-6009 or request a quote online.