Adjusting Water Heater Temperature for Safety

The Ideal Temperature Setting

The recommended water heater temperature is 120°F (49°C), which balances comfort, safety, and energy efficiency. At 120°F, water is hot enough for comfortable bathing and effective dishwashing while reducing the risk of scalding — water at 140°F can cause third-degree burns in just five seconds. However, some situations may require 140°F, such as households with immunocompromised individuals (higher temperatures inhibit Legionella bacteria) or dishwashers without built-in heating elements.

Adjusting a Gas Water Heater

Gas water heaters have a temperature dial on the gas valve near the bottom of the unit. Many dials use descriptive labels rather than exact temperatures — the common settings are Vacation, Low, Hot, and Very Hot. The notch between Low and Hot typically corresponds to about 120°F. Turn the dial to your desired setting and wait 24 hours before testing — it takes time for the entire tank of water to reach the new temperature. Test with a cooking thermometer at the faucet closest to the water heater.

Adjusting an Electric Water Heater

Electric water heaters have thermostats behind access panels on the side of the tank. Turn off the circuit breaker before removing the access panel and insulation. The thermostat has a temperature dial that can be adjusted with a flathead screwdriver. If your heater has two elements (upper and lower), adjust both thermostats to the same temperature. Replace the insulation and access panel, then turn the breaker back on. Wait 24 hours and test the temperature at a faucet.

Anti-Scald Measures

Even at the recommended 120°F setting, water can still cause burns with prolonged exposure, particularly for young children and elderly individuals. Consider installing anti-scald (thermostatic mixing) valves at point-of-use locations such as bathtubs and showers — these mix cold water with hot to deliver water at a safe, consistent temperature. Pressure-balanced shower valves prevent temperature spikes when someone flushes a toilet or runs another fixture, which is a common cause of shower scalding incidents.