Below is a list of the three most common risks associated with hot water systems, what to look out for and how to avoid them. 




Legionella bacteria can thrive in water between 30 and 50°C and can live in water up to 60°C. Exposure to this particularly harmful bacteria can cause pneumonia and flu-like symptoms.  Breathing in water vapour can also lead to infection of the lungs and can be fatal. Older hot water systems are prone to Legionella as they do not heat up as efficiently. Water stored at over 60°C for over an hour will kill any of this bacteria.



Did you know? Ninety percent of hot water burns in the home occur in the bathroom.

By law, when you install a new hot water system, you need to temper it to a maximum of 50°C for any bathrooms. Kitchens and laundries are allowed to have separate, un-tempered hot water supplies that can go hotter.

  • Tempering valves come pre set to 50°C and must be changed every five years to ensure they are working correctly. Plumbers must install these with every hot water install.
  • In places such as disabled bathrooms and aged care homes, a plumber may be required to install a TMV (thermostatic mixing valve). A TMV is a more accurate warm water mixing valve. These are adjustable and are normally set at 42°C to allow for people who may not have the same reaction speed to hot water burns.
  • Continuous flow systems do not require much ongoing maintenance or extra valves like storage tanks do. Most continuous flow hot water systems are available as a 50°C maximum pre-set temperature.


Explosions/Bad Leaks

A temperature and pressure relief (TPR) valve needs to be installed on every storage tank to prevent hot water systems from blowing up. It is normal for these to leak a little bit and very important to know not to plug them off.

  • When replacing a hot water tank that is inside the home, ensure it is fitted with an emergency shut-off valve and a tray underneath it to catch leaks.
  • An important thing to look out for in your HWS is rust. Rust can eat through the tank of your system and end up all over the floor where the system is located.
  • For heaters located inside the home, it is important to regularly check for rust and flush out sediment in . These are at high risk when not serviced. You can do this by opening the hot water tap over your bath and filling it up. If the water is changing to a yellow/brown colour by the end, it’s time to think about a new heater.


To get more handy information and maintenance tips on hot water systems, please download our free e-book guide.

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