When your water heater finally quits, you've got a decision to make in a hurry: replace it with another storage tank, or upgrade to a tankless unit? Both heat water with gas; they just do it very differently. Here's the real-world comparison for Toronto homes.
The quick answer
A traditional tank keeps 40–60 gallons of water hot and ready around the clock. A tankless unit heats water on demand as it flows through the unit — so it never runs out, but it can only heat so much at once. Tankless costs more up front and lasts longer; tank costs less and is simpler to service.
| Storage tank | Tankless | |
|---|---|---|
| Installed cost (2026, GTA) | $1,800 – $3,000 | $3,800 – $6,500 |
| Lifespan | 8 – 12 years | 18 – 20+ years |
| Hot water | Limited by tank size; can run out | Endless, but limited flow rate |
| Space | Large floor-standing tank | Compact wall-mounted unit |
| Energy use | Reheats standby losses 24/7 | Heats only when you need it |
| Maintenance | Occasional flush | Annual descaling (hard water) |
When a tankless makes sense
- You run out of hot water with your current tank
- You're staying in the home long-term (the longer lifespan pays off)
- You want the floor space back in a small utility room
- You're already renovating and the venting/gas can be upgraded cleanly
The catch: tankless units have a maximum flow rate. Run two showers and the dishwasher at once in a big household and a single unit can struggle. Proper sizing — and sometimes a larger unit or two in parallel — matters. In Toronto's hard water, an annual descale keeps a tankless running at full efficiency.
When a tank is the smart choice
- You want the lowest up-front cost
- Your hot-water demand is modest and predictable
- Your existing venting and gas line already suit a tank
- You may move within a few years
A modern high-efficiency tank is reliable, cheap to replace, and easy for any technician to service. For many households it's simply the sensible option.
Don't forget venting and gas
Switching from a tank to a tankless usually means new venting and often a larger gas line, because tankless units fire at a much higher BTU rate when running. That's part of why the installed cost is higher — and why it should always be done by a licensed gas fitter. A tankless installed on an undersized gas line won't perform and isn't safe.
Signs it's time to replace either one
- Rusty or discoloured hot water
- Water pooling around the base of a tank
- Rumbling or popping sounds (sediment buildup)
- Not enough hot water, or it runs out fast
- The unit is past its expected lifespan
We cover the warning signs in more detail in signs your water heater needs replacing.
Not sure which fits your home and budget? Alderwood Mechanical installs and services both tank and tankless systems across Toronto and the GTA. We'll size it right and give you an upfront price. Call 437-229-8618.
Alderwood Mechanical serves Toronto, North York, Scarborough, Etobicoke, Mississauga, Vaughan, Markham, Oakville, and surrounding GTA. G1 licensed gas fitters. No contracts. Upfront pricing.
Water heater on its last legs?
We'll help you choose right.
Tank or tankless, sized properly and installed by licensed gas fitters — across Toronto & the GTA.