What is the Right Water Heater
Temperature Setting for Safety?

Generally, water heaters are set to about 140 degrees Fahrenheit. At this temperature, harmful bacteria such as Legionella that could grow in hot water lines are killed. Families with small children or adults that may be physically challenged have to be careful since it would only take about 5 seconds for someone to be severely scalded by 140 degree water. At 155 degrees it would only take 1 second to cause serious scalding injury.

However, reducing hot water to a less dangerous temperature in the 115 to 120 degree range creates an ideal breeding condition of Legionella bacteria. At that low temperature range, water may not be hot enough for comfortable baths or showers or adequate for laundry. Hot water also depletes more quickly when a water heater is set at lower temperatures.

The solution is installing a "water mixer" device which permits water to be heated to a desirable 140 degrees F that will kill harmful bacteria, but sets a lower maximum temperature to be distributed to faucet taps. Installing a water mixing valve will combine cold water with hot water to prevent scalds while eliminating the risk of Legionella in your water lines. Your Phoenix area plumber can recommend an affordable system that balances convenience with family safety.

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