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What is the Best Temperature to Set My Water Heater at ?

What is the Best Temperature for my Hot Water Heater?

Water Heater There are two risks that come with the temperature of the water heater. Too high and the users can get scaled. Too low and you could risk pathogens, especially Legionella, which in turn causes Legionnaires’ disease.

Minimum Temperatures

  • 32 to 42 °C (90 to 108 °F): Optimal growth range
  • 48 to 50 °C (118 to 122 °F): Can survive but will not multiply
  • 50 °C (122 °F): 90% of bacteria will die in 80–124 minutes
  • 60 °C (140 °F): 90% of bacteria will die in 2 minutes
  • Above 70 °C (158 °F): Legionella dies almost instantly

Maximum Temperature

Setting the temperature to high will cause the users to get scaled by the water. This is easily done when you first open the tap because the water that has been sitting in the pipe has cooled down, by the time the water from the tank reaches the tap most users think it is fine until the heated water hits their skin and scales them. Some people, especially the elderly are at more risk because they have less sensitivity which causes them to move slower away from the scalding water. Young children are also at a higher risk because they have thinner skin. The Consumer Product Safety Commission (CPSC) recommends setting the water tank to 49 °C (120 °F).


Most of the current model dishwashers recommend that you set it to 49 °C (120 °F). Most of theses will also heat the interior as needed with heaters built in. You may want to check specifications if you own an older dishwasher, because dishwasher detergent varies but it has been said that between 50 and 60 °C is when it works best. Another alternative is cold water dishwasher detergent that works at any temperature.

Different Views

The Canadian Commission on Building and Fire Codes (CCBFC) and their top experts have refused the minimum temperature for the hot water tank at 49 °C. Top trusted organizations are telling homeowners to lower their hot water tank to 49 °C, to prevent from scalds at the tap. The main thing is that the water must be stored in the hot water tank at a high temperature to be a precaution against bacteria. While having the tank holding the water so hot, to avoid the scalds you can always place anti-scald mixing valves.

Concerns about piping

Cooper will cool down faster than PEX, but given enough time the temperature of both pipes would eventually cool down to the same temperature. Another question posed is if it is worthwhile to insulate the pipes. While it will keep the water in the pipes warmer for longer it will still cool.

In a study of over a 500 day period Legionella grew a bit faster in PEX than cooper, however over 800 days there was little to no difference in the growth between the two pipes.

Dead Legs:

Dead legs are branches that are capped off, that contain idle water that is the prefect condition for breeding grounds for the bacteria which than can contaminate the entire system. This is not surprising due to the fact that the water in the dead leg would get warm but not hot enough to kill the bacteria.

A valve should be installed as close as possible to the main line to minimize the risk.


The best scenario looks like to be buying and installing anti-scald valves at all the taps and showers. This could be installing them under the sink or in a shower valve. This means setting the tank to 60°C and setting each human point at 49°C and even possibly setting the human points that are used by children most to 43°C. Other appliances like the dishwasher, washing machine, humidifier will all get the full amount of heat which is set to 60°C with no issues of water temperature.

The only downside to buying the anti-scald valves is the price that could end up being associated with it. For sinks they are relatively easy to install, but when it comes to showers and tubs, they could be difficult to install.

Do not wait for the trouble, but have a licensed technician service your old hot water heater in Toronto, GTA before it causes you any problems. Upgrade your old owned or rental hot water heater to a new energy efficient rental or owned unit and enjoy the comfort and safety of your home.


We will be happy to assist you with any questions or enquires regarding your water heater needs. Our team of dedicated and experienced professionals aim to provide homeowners with fast and reliable response and water heating solutions.

If you are looking to replace your old water tank to energy efficient model call DeMark Home Ontario -heating, cooling and hot water heating expert for more detail on specifications and hot water heater installation. Call today at 647-847-2998 or submit your request online.

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Effective August 2007, gas code requires technicians working on venting to replace black ABS vent pipe with white UL-certified vent pipe.

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