Lowering hot water temperature

Lower the temperature of your hot water heater

The easiest way to prevent burns from hot tap water is to turn down the setting on your hot water heater to 49°C (120° F). Do this only if you can easily see the thermostat dial on the outside of the tank.

Note: A third degree burn (characterized by blistering, intense pain and permanent tissue damage) will occur in children in only 5 seconds when water temperature is 60°C (140°F).  At 55°C (130°F), a third degree burn will occur in 15 seconds, while the time to produce a third degree burn extends to at least 5 minutes when water temperature is 49°C (120°F).  Ostrow LB,  Bongard FS,  Sacks ST,  McGuire A,  Trunkey  DD.  Major burns resulting from scalds: The California burn registry experience.  JBCR 1985; 6 (4):  350-352.

If you choose this option, there are some important things you should know:

If anyone living in your home has a long term or serious illness, check with your doctor before turning down your water heater. DO NOT lower the temperature of your water heater if anyone in your home has a weakened immune system, including the elderly, those who have chronic obstructive pulmonary disease, HIV/AIDS, an organ transplant, cancer or is taking medicine that suppresses the immune system.

People with these conditions are more at risk for legionnaires' disease, a type of severe pneumonia.

Read the manual for your water heater before changing the setting on the thermostat dial. If you do not have a manual, contact the company that made the water heater. Their number should be posted on the heater. If you rent your water heater, contact the rental company.

  • Gas and oil-fired water heaters have thermostat dials located on the outside of the tank. If the dial has numbers on it, turn the dial down to 49° C or 120° F. If the dial has words like Hot, Warm (or Medium), and Vacation, turn the dial to the Warm or Medium setting. That is approximately 49° C. (The water will still feel quite hot at your taps, but will not cause a scald burn in seconds.)
  • Do not lower the temperature of your water heater below 49° C or a Medium setting. A lower setting can lead to the growth of the bacteria that causes legionnaires' disease.
  • After adjusting the temperature, wait 24 hours and then test the temperature of your tap water again using a thermometer. Sometimes a heater requires several adjustments before you get the right temperature.
  • Water heaters may continue to pose scalding risks, even when turned down. Be sure to practice safe bathing and to supervise children closely.
  • If you have an electric water heater, do not lower the temperature setting below 60° C. The bacteria that causes legionnaires' disease grows more easily in some electric water tanks because of the way they are designed. You can still lower your water temperature by installing safety valves. Talk to a qualified plumber, the company that made your heater, or the rental company for your water heater.

Install mixing valves to control the temperature of your hot tap water

Devices called mixing valves or tempering valves can be installed in the plumbing pipes at various places. These valves control the temperature of the water before it leaves your taps. Inside your water heater, the temperature can be scalding hot, but the valve will mix in cooler water if needed, to ensure that water at the tap is no hotter than 49° C.

Talk to a qualified plumber or the rental company for your water heater for proper installation of mixing valves.

There are three ways you can use mixing valves:

  • You can install a master mixing valve right at your water heater. This will control the tap water temperature everywhere in your household.
  • Or, you can install mixing valves in the hot water pipes that go to separate areas of your household – for example, to the bathroom and kitchen.
  • Or, you can install mixing valves at individual taps – for example, at each sink and bathtub.

If you do not have access to your water heater:

Turning down the thermostat of large water heaters in multi-unit buildings is NOT recommended. Harmful bacteria can grow in large water heaters set too low. Also, there may not be enough hot water for everyone in the building.

If you live in an apartment or multi-unit building and do not have access to your hot water heater:

Ask your landlord or property manager to make sure that the hot water at your taps is no hotter than 49° C (120° F). One option is to install mixing valve(s) in the hot water pipes so that the hot water is a safer temperature everywhere in your apartment. An alternative is to install a mixing valve at each of the taps in your kitchen and bathroom.

If you cannot get mixing valves installed in your hot water pipes, you can use other devices to help protect your child from tap water scalds.

Other devices

Some other devices available include:

'Anti-scald' or 'shut-off' devices: These are products that attach to the faucet or tap. Some models actually replace the faucet. If the water gets too hot, these devices slow down the water to a trickle. You can restart the water by mixing more cold water into the tap.

Anti-scald devices are available in safety specialty shops, some hardware stores and some children's product stores. Not all models fit on all kinds of taps, however, and although these products are promoted as "do it yourself" items, they may require adapters or the help of a plumber to install them.

Tap guards: A tap guard blocks your child's access to the hot water tap. These can be found in many home improvement and child safety stores.