Hot water is essential for daily tasks, from personal hygiene to cleaning. Understanding the appropriate temperature for household water is important for user safety and system efficiency. Achieving the right balance prevents hazards and optimizes your home’s water system.
Setting a Safe Temperature
To prevent scalding injuries, the recommended maximum temperature at the faucet is 49°C (120°F) for most households, especially those with young children, elderly individuals, or people with sensory impairments. Water hotter than this can cause severe burns; for instance, 60°C (140°F) can cause third-degree burns in five seconds, while 68°C (155°F) can cause burns in one second.
To enhance safety, thermostatic mixing valves (TMVs) can be installed, especially when the water heater is set to a higher temperature. These valves blend hot and cold water to deliver a consistent, safe temperature at the tap, typically around 49-50°C (120-122°F). TMVs ensure water dispensed at the point of use remains within a non-scalding range.
Balancing Hygiene and Energy Use
Maintaining appropriate water temperatures is important for preventing the growth of harmful bacteria, specifically Legionella. This bacterium thrives in warm water environments, with optimal growth between 20°C (68°F) and 45°C (113°F). To control Legionella, hot water storage tanks should maintain water at 60°C (140°F) or higher, as most bacteria are eliminated within minutes at this temperature.
While higher storage temperatures address bacterial concerns, they also impact energy consumption. Heat loss from the water heater and piping increases with higher temperatures, leading to greater energy use. Lowering the thermostat to 49°C (120°F) can reduce utility costs by 6 to 10 percent compared to a 60°C (140°F) setting. A common strategy is to keep the water heater at 60°C (140°F) to inhibit bacterial growth and install TMVs to deliver cooler, safe water at the taps, balancing hygiene and energy efficiency.
How to Adjust Your Water Heater
Adjusting your water heater’s temperature involves locating its thermostat. Before making any adjustments, turn off the power supply for electric water heaters at the circuit breaker or the gas supply for gas models.
Electric water heaters usually have two thermostats, one for each heating element, often concealed behind access panels. These typically require a flathead screwdriver, and both should be set to the same temperature. Gas water heaters usually feature a single temperature dial on the gas valve near the tank’s base, which might indicate settings like “warm” or “hot” instead of specific temperatures.
After adjusting the thermostat, restore the power or gas supply. Wait several hours for the water temperature to stabilize before testing. Use a thermometer to verify the temperature at a faucet furthest from the water heater, ensuring it aligns with safe levels. Some modern tankless or smart water heaters may offer digital controls, simplifying adjustments.