The short version
- Most tanks give eight to twelve years. Past twelve, money spent on repairs is money spent on a tank that owes you nothing.
- Peel Region water is moderately hard. Heating hard water leaves sediment in the bottom of the tank, and that sediment is what shortens its life.
- Five signs matter: rusty hot water, a rumbling noise, hot water running out sooner, damp around the base, and the date on the rating plate.
- A puddle under the tank is not a repair. Once the steel has rusted through there is no fix, only a replacement.
The honest answer: eight to twelve years
Most tanks in this area give eight to twelve years of service. Some reach fifteen. Some fail at seven. The brand on the front has less to do with that spread than two other things: the water running through it, and whether anyone ever serviced it.
Natural Resources Canada says it plainly in its Water Heater Guide. Water quality is the single most important factor affecting the life of the water heater. Everything else is a distant second.
So a serviced tank can outlast the one in the house next door by years. That part you have some control over. The rest you do not.
Why Mississauga water is hard on a tank
Our water comes out of Lake Ontario. Peel Region's own 2023 water quality report puts hardness in the South Peel system at 120 to 130 mg/L, which is 7.0 to 7.6 grains per gallon, and calls the water moderately hard.
That matters because of what heating does to hard water. The minerals drop out and settle on the floor of the tank as sediment. On a gas tank the burner sits underneath, so it ends up heating through a layer of grit before it heats any water.
- The tank runs longer for the same hot water, so the gas bill creeps up.
- The steel at the bottom gets hotter than it was meant to, which is hard on the glass lining.
- Sediment holds water against the steel, and that is where rust starts.
There is a second line of defence inside every tank, called an anode rod. Natural Resources Canada describes it as a magnesium or aluminium rod fitted through the top, there to corrode instead of the tank. How fast it dissolves depends on the mineral content of the water. When the rod is used up, the tank is next in line.
Five signs yours is near the end
One of these on its own does not mean you need a tank tomorrow. Two or three together usually do.
| Sign | What it usually means | What to do |
|---|---|---|
| Rusty or brown hot water | The anode rod is gone and the lining is corroding | Book a look. If only the hot side is discoloured, the tank is the source |
| Rumbling or popping as it heats | Sediment on the floor of the tank, with water boiling under it | A flush may help. On an older tank it often will not |
| Hot water runs out sooner than it used to | Sediment taking up volume, or a broken dip tube | Worth a service visit. Both are straightforward to diagnose |
| Damp or rust around the base | A slow leak, either from a fitting or from the tank itself | Find out which one today. A tank leak only gets worse |
| Past twelve years on the rating plate | It has done its job | Plan the replacement instead of waiting for the flood |
That last one is worth two minutes. The rating plate is the label on the side of the tank. Most makers code the month and year of manufacture into the first characters of the serial number, so a technician can date your tank on the spot.
The water heater maintenance that buys you years
It is one visit a year and a short list. The list is the same whether the tank is gas or electric.
- Drain and flush the tank. This is how the sediment leaves. Bradford White, one of the brands on our pricing list, treats the flush as the core of an annual service.
- Check the anode rod. If it has dissolved away, a new rod costs a fraction of a new tank.
- Test the temperature and pressure relief valve. Every tank has to have one. It is what lets water out if the tank goes too hot or too high on pressure, and it is the last part you want seized shut.
- Check the temperature setting. Set too hot it scalds and wastes gas. Set too cool it can let bacteria grow in the tank. This is one to have set properly rather than guessed at.
How to flush a hot water tank, and when to leave it
A flush is a garden hose on the drain valve and a careful few minutes, and plenty of homeowners do their own. Two cautions. On a tank that has never been flushed, sediment can jam the drain valve open so it will not close again, so know where your shut off is before you start. And on a tank well past ten years, a first flush sometimes finds a weak spot rather than fixing one. If you are unsure, have it done on a service visit.
Of that list, the flush and the anode rod are the two that change how long the tank lasts. The other two are safety.
Repair or replace, and what a new one costs
The rule is simple. A leak at a fitting, a valve or a connection is a repair. A leak out of the tank itself is not, because there is nothing to repair. A water heater repair visit tells you which of the two you have, usually in the first ten minutes.
On a tank past twelve years we will normally say so rather than sell you a repair. Putting a few hundred dollars into a tank that owes you nothing is a poor trade, and we would rather tell you that than take the work.
Installed prices are published on the pricing list, and they include hauling the old tank away. A 50 gallon conventional vent tank starts at $1,950 + HST and a 40 gallon is $2,100 + HST. Power vented tanks run from $2,250 + HST up to $3,500 + HST for a 75 gallon. A tankless water heater starts at $3,750 + HST. Financing is available from $42 a month on qualifying installs.
Two reasons to plan it rather than wait it out. A planned replacement happens at a time that suits you, and a failed one does not. And a tank that lets go in a finished basement costs far more in flooring than the tank ever did.