It remains difficult to neatly summarise temperature regulations for hot water systems in Queensland.
While there is a consistent domestic standard, there are temperature limitations which apply to sites where the young and the aged are most at risk of being scalded.
The Queensland State Government is strict about requiring that any hot water that is stored in residential hot water systems is at least 60 degrees Celsius. Why? Because potentially deadly Legionella can’t survive at 60 degrees Celsius. The high temperature prevents Legionella from multiplying in the hot water system and plumbing.
However, being exposed to water at 60 degrees Celsius causes second-degree burns in just three seconds. Add another two seconds and the scalding is extremely serious, meaning third-degree burns.
So Queensland regulations forbid anything more than 50 degrees Celsius being delivered to domestic hot water taps and showers. That 10-degree drop is the difference between serious injury and almost no risk from several minutes of exposure.
While 50 degrees Celsius is the maximum temperature for flowing water in most households, the exception is for aged care facilities, hospitals, kindergartens and schools. In such buildings, the flowing water temperature from outlets is limited to 45 degrees Celsius to reduce the risk of scalding to the most vulnerable.
So how is this controlled? All water heating systems must use a hot water tempering valve (or thermostatic mixing valve). There are different types of hot water tempering valves, but all of them mix cold water in with the scalding 60 degree water to achieve the safe temperature.
As such, it’s important to maintain your hot water system. They should not be turned off unnecessarily and, if they are, should be heated at 60 degrees Celsius for at least half an hour before using the hot water.
Never turn a hot water system down. Any adjustments to thermostat settings should be done by a licensed plumber.
The Queensland Plumbing and Wastewater Code was amended in 2013 to remove the requirement to install an energy efficient hot water system – such as gas, solar or heat pump – in every building. This means homeowners can choose a hot water system that best suits their needs, including an electric system. However, a hot water tempering device is required to be fitted to all systems.
To maintain, test, repair or replace your hot water system, make sure you consult a fully licensed plumber.