Set a storage water heater to about 60 °C (140 °F). Government of Canada guidance recommends that temperature to prevent the growth of bacteria such as Legionella. Then limit the water delivered to taps, showers and tubs to about 49 °C (120 °F) with a mixing valve, because water at 60 °C can scald in seconds. Measure at the tap with a thermometer; tank dials are often unmarked.
- Store hot, deliver warm: about 60 °C in the tank for Legionella control, about 49 °C at the tap for scald safety.
- A thermostatic mixing valve at the tank, or anti-scald valves at fixtures, is how you get both at once.
- At 60 °C, hot water can cause a scald in under five seconds; a child's skin burns far faster than an adult's.
- Turning a tank well down to save energy or prevent scalds invites bacterial growth, especially in electric tanks.
- Check with a thermometer at a tap: gas dials often have no numbers and electric thermostats sit behind live panels.
01 /What temperature should my hot water tank be set at?
Set a hot water tank to about 60 °C (140 °F). The Government of Canada's guidance on water temperature and scalds recommends setting the water heater to 60 °C to prevent the growth of harmful bacteria such as Legionella, and the Public Health Agency of Canada's Legionella page describes keeping a home water heater at a minimum of 60 °C. The same guidance recommends automatic mixing valves on faucets, showers and tubs, or an anti-scald mixing valve on the water heater, set to deliver 49 °C (120 °F).
| Where | Target | Why |
|---|---|---|
| In the tank (storage) | About 60 °C (140 °F) | Keeps stored water too hot for Legionella and other bacteria to thrive |
| At taps, showers and tubs (delivery) | About 49 °C (120 °F) | Limits scald risk, especially for children, older adults and people with reduced sensation or mobility |
The two numbers are not a contradiction. The tank protects against bacteria; the mixing valve protects people. Setting a single compromise temperature, say 50 °C in the tank, gives up some of both.
02 /Why does 60 °C matter for Legionella?
Legionella bacteria multiply in warm water. The Public Health Agency of Canada notes they grow in warm water temperatures, especially between 20 °C and 50 °C. A storage tank kept in that range, particularly the cooler water at the bottom, can let them grow, and people can be infected by breathing in fine droplets, such as shower spray.
Natural Resources Canada's Water Heater Guide gives the same caution from the energy side: lowering the temperature too much may promote bacterial growth, especially in electric storage tanks, and increases the chance of running out of hot water because you mix in less cold. A common explanation for singling out electric tanks is that their lower element sits some way above the bottom of the tank, which can leave the coolest water below it warm but never hot.
The risk matters most for people most vulnerable to Legionnaires' disease. PHAC lists higher-risk groups including people over 50, people who smoke, people with chronic conditions such as diabetes or COPD, and people with weakened immune systems. In those households, keeping the tank at 60 °C with a mixing valve is especially worth doing.
03 /How fast can hot water scald?
Very fast. Natural Resources Canada's Water Heater Guide includes a scalding guide showing the approximate time for a scald at each temperature. The Government of Canada's scald page adds that a child's skin burns in a quarter of the time it takes an adult's.
| Water temperature | Approximate time to scald |
|---|---|
| 52 °C (125 °F) | 1.5 to 2 minutes |
| 54 °C (130 °F) | about 30 seconds |
| 57 °C (135 °F) | about 10 seconds |
| 60 °C (140 °F) | less than 5 seconds |
| 63 °C (145 °F) | less than 3 seconds |
| 66 °C (150 °F) | about 1.5 seconds |
| 68 °C (155 °F) | about 1 second |
04 /How do I get 60 °C in the tank and 49 °C at the tap?
Install a thermostatic mixing valve, sometimes called a tempering valve, on the hot outlet of the water heater, or use anti-scald valves at fixtures. A thermostatic mixing valve blends hot water from the tank with cold to hold a set delivery temperature, and adjusts as the tank temperature or supply pressure changes.
Natural Resources Canada notes there are requirements for installing tempering valves or at-use devices to lower delivered temperature, and many new bathrooms must have anti-scald shower and tub valves; the exact requirement depends on your province's plumbing code and the type of fixture. A plumber fits a tank-mounted mixing valve in a short visit, and it is worth asking for whenever a water heater is replaced. See hot water tank installation.
05 /How do I check and adjust my water heater temperature?
Measure at a tap with a thermometer, adjust the heater, then measure again a few hours later. Natural Resources Canada points out that gas water heater dials usually have no numbers, so the tap reading is the only reliable guide.
- Pick the right tap
Use the hot tap closest to the water heater for the tank temperature. If you have a mixing valve, a bathroom tap shows the delivered temperature.
- Run it
Let hot water run for two or three minutes, until the temperature stops rising.
- Measure
Fill a cup and put a cooking or candy thermometer in it straight away.
- Adjust the heater
Gas: turn the dial toward or away from the hotter setting in small steps. Electric: with the breaker OFF, remove the access panels and set both thermostats to the same value; Natural Resources Canada suggests considering a qualified service person for this. Heat pump and tankless: use the display.
- Wait and remeasure
Give a tank several hours to reach the new setting, then measure again. Repeat until the nearest tap reads about 60 °C.
- Set the mixing valve
Adjust the mixing valve until bathroom taps and the tub deliver about 49 °C.
06 /Should I lower my water heater temperature to save energy?
Only modestly, and not below about 60 °C in the tank. Lower settings reduce standby heat loss a little, but they increase bacterial risk and make you run out of hot water sooner, because more hot water goes into each shower. The bigger savings are in using less hot water and reducing standby loss: low-flow showerheads, insulated pipes near the tank and an efficient heater. Natural Resources Canada's guide covers those in detail.
| Situation | Suggested approach |
|---|---|
| Everyday use | Tank near 60 °C; mixing valve delivering about 49 °C |
| Young children or older adults at home | Same, and confirm the mixing valve or anti-scald valves work |
| Running out of hot water | Keep 60 °C in the tank; a mixing valve stretches supply; see not enough hot water |
| Away for a week or more | VACATION setting; on return, set back to normal and run each hot tap for a few minutes |
| Tankless water heater | Set the output temperature directly, usually at or below delivery temperature; follow the manual |
| Heat pump water heater | Use the mode that meets demand; check the tank setting reaches about 60 °C or that the unit has a periodic high-temperature cycle |
To see what your setting costs, the Energy Cost Comparer uses your inlet and set temperatures with your own gas and electricity prices. For heaters that cannot keep up at a safe setting, see what size water heater.
FAQQuestions people ask
Is 60 °C too hot for a water heater?
No. About 60 °C is the recommended storage temperature for controlling Legionella in Canada. It is too hot to deliver at taps, which is why a mixing valve or anti-scald valves should bring delivered water down to about 49 °C.
Is 49 °C hot enough to kill bacteria?
No. 49 °C is a safe delivery temperature for people, not a disinfection temperature. The tank itself should be kept near 60 °C, and a mixing valve reduces the temperature at the taps.
What setting is 'Hot' on my gas water heater dial?
It varies by control and there are usually no numbers. Measure at the nearest hot tap with a thermometer after the tank has had several hours to recover, and adjust in small steps.
Why is my water too hot even at a normal setting?
A short draw can deliver water from the hottest top layer, which can be hotter than the thermostat setting. If water is dangerously hot or keeps getting hotter, the thermostat or gas control may be failing; turn the heat down or off and call a technician.
Does turning down the water heater save money?
A little, through lower standby losses, but not below about 60 °C in the tank. Using less hot water and insulating pipes near the tank save more without the bacterial risk.
Do I need a mixing valve?
It is the practical way to keep 60 °C in the tank and 49 °C at the tap. Some jurisdictions require tempering or anti-scald devices for new work; a plumber can tell you what applies to your installation.