What's the Right Temperature for Your Hot Water?
The recommended hot water heater temperature is typically set between 50°C and 60°C. This range offers a good balance between preventing the growth of harmful bacteria like Legionella and minimising the risk of scalding injuries. For most households, 55°C is considered a safe and effective temperature setting.
- Set between 50°C and 60°C for safety and efficiency.
- 55°C is often the ideal compromise temperature.
- Lower temps risk Legionella; higher temps risk scalding.
- Check your specific water heater manual for guidance.
When you first get a new water heater, or if you've recently had maintenance, the factory default is often set higher than necessary, sometimes as high as 70°C. While this might seem good for killing germs, it significantly increases the risk of serious burns, particularly for children and the elderly. It also wastes energy by heating water to unnecessarily high levels, which then requires mixing with cold water at the tap to be usable. Finding that sweet spot is key.
Consider how you use hot water. If your water heater tank is located in a very cold environment, you might need to set it slightly higher to compensate for heat loss. However, for the vast majority of situations, staying within the recommended range is the most sensible approach.
Why Temperature Matters: Safety vs. Efficiency
Why is this temperature range so important? It boils down to two primary concerns: your safety and the efficiency of your appliance. Getting it wrong can lead to either unpleasant bacterial growth or dangerous burns.
The Risk of Too Low a Temperature
Setting your water heater too low, below 50°C, especially if it hovers around 40°C, creates an environment where Legionella bacteria can thrive. These bacteria are found naturally in fresh water. If they get into a water system and are aerosolised (like in a shower spray), they can be inhaled and cause Legionnaires' disease, a severe form of pneumonia. While a household water heater is less likely to be the sole source of a large outbreak compared to large building systems, the risk is still present and should be taken seriously.
Maintaining a temperature above 50°C significantly inhibits Legionella growth.
The Danger of Too High a Temperature
On the other end of the spectrum, water heated above 60°C poses a substantial scalding risk. It only takes a few seconds of exposure to hot water at 60°C to cause a third-degree burn. At 70°C, a burn can happen in less than a second. This is a critical consideration for any household, but especially if young children, elderly individuals, or those with reduced mobility or sensory perception are present. Blending hot and cold water at the tap is a common practice, but it doesn't negate the initial danger from the tank itself and the pipes.
Furthermore, excessively high temperatures can increase the rate of mineral buildup within your water heater tank and pipes, potentially leading to reduced efficiency and requiring more frequent water heater repair.
Adjusting Your Water Heater Temperature
How do you actually change the temperature on your hot water heater? The process varies slightly depending on whether you have an electric or gas model, and the specific brand, like an Ariston water heater, or type of unit, such as an under sink water heater.
For Electric Water Heaters
Most electric water heaters have a thermostat control accessed behind a panel on the unit. You'll typically need to turn off the power supply at the breaker first for safety. Once the panel is removed, you'll see one or two thermostats, each with a dial or screw. Follow your appliance's manual to adjust the temperature dial to your desired setting. Remember to replace the panel and restore power only after you're done. It might take a few hours for the water to reach the new temperature.
Test the water temperature at a tap furthest from the heater before concluding the adjustment. Allow adequate time for the new temperature to stabilise throughout the system.
For Gas Water Heaters
Gas water heaters usually have a simpler dial control located on the gas control valve near the bottom of the tank. This dial typically has settings ranging from 'Low', 'A', 'B', 'C', 'Hot', or marked with temperatures. Consult your water heater's manual to understand what each setting corresponds to. You'll be adjusting this dial to reach your preferred temperature within the safe range.
Carefully observe the temperature markings on your specific model; exact settings can vary.
Always consult your water heater's specific instruction manual before making any adjustments. This is the most reliable source for precise instructions, safety warnings, and details relevant to your particular model, whether it's a standard water heater tank or a compact undersink water heater.
What If You're Unsure About Water Heater Replacement?
If your water heater is old, inefficient, or you're contemplating a water heater replacement, this is a good time to evaluate its settings. For any concerns about the process or the safety of your current unit, seeking advice from a qualified plumber is always the wisest step. They can ensure adjustments are made safely and correctly.