Hot Water Safety

Hot Water Safety: Prevent burns, disease and death

Use caution when dealing with hot water!


Hot water can be dangerous.  Adults and children alike can be scalded or become sick with Legionnaires’ disease if your hot water system is not setup properly.

Furthermore, installing hot water systems is dangerous.  Improperly installed systems can cause carbon monoxide to enter the home or cause home explosions.

We advise you to have a licensed professional install, tune and maintain all your hot water systems.  Doing things wrong could be a life or death situation.  



Hot water safety checklist

  • Have a licensed professional install your hot water systems
  • Have an annual inspection and maintenance of your hot water systems by a licensed professional
  • Keep children away from hot water heating systems
  • Install anti-scald devices on every hot water fixture
  • Set your storage tank water heater no lower than 140° F to prevent Legionnaires’ disease
  • Install a mixing valve to reduce the output temperature of your hot water heater to 120°.  This protects your family against scalding
  • Install carbon monoxide detectors, preferably hardwired or wirelessly linked detectors on all levels of your home or office and in all bedrooms
  • Consider a tankless hot water heater to enable precise control over output temperature
  • Consider a sealed combustion hot water heater (tankless or power vent hot water heater) to ensure exhaust gasses are vented outside
  • Test the air around your hot water heater to ensure it is not emitting excess levels of NOx (Nitrogen Oxide) or CO (Carbon Monoxide) into your home

Scalding Information

How Fast you can get scalded by hot water

Hot water 154 degrees fahrenheit or warmer will scald you instantaneously.  It takes 2 seconds for a first-degree burn with 140 degree fahrenheit water, and 3 minutes for a first-degree burn with 120 degree fahrenheit water.  It is critical for you to keep your hot water tap temperature no warmer than 120 degrees.

Temperature Time for First Degree Burn Time for  Second Degree Burn (Permanent)
110° F Normal Hot Shower – No Burn Normal Hot Shower – No Burn
120° F 3 Minutes 9 Minutes
126° F 30 Seconds 90 Seconds
131° F 5 Seconds 25 Seconds
140° F 2 Seconds 5 Seconds
154° F Instantaneous 1 Second
How fast hot water can scald you temperature graph

Further information / References

ASSE Plumbing “Understanding Potential Water Heater Scald Hazards”, 2012

ASSE Plumbing “Guidelines for Temperature Control Devices in Domestic Hot Water Systems”, 2017