Australian Standards require that hot water shall be stored at not less than 60 degrees C to avoid the likelihood of legionella bacteria growth.
Australian Standards also requires that new heated water installations shall deliver heated water to fixtures (like basins and showers) 1) at 45 degrees or less for personal hygiene for the aged, the sick, children or people with disabilities in health care facilities and aged care buildings, early childhood centres, primary and secondary schools and nursing homes or similar facilities for the aged, the sick, children or people with disabilities; and 2) at 50 degrees for personal hygiene purposes for all other situations (domestic houses, hotels etc).
If a maximum temperature of 45 degrees is required a thermostatic mixing valve should be used. If a maximum of 50 degrees is required then a thermostatic mixing valve, or tempering valve should be used. (in some cases an appliance can have a factory set maximum temperature of 50 degrees that also meets Australian Standards.
There are specific tests that are required to be completed annually on both types of valves. The test on a thermostatic mixing valve is involved and is usually a compliance requirement for the facility where it is installed. The tests on a tempering valve is less rigorous. One reason to test these valves is to ensure they are working if the cold supply to the valve is stopped. When operating correctly both valves will stop all water supply through the valve (hot and cold water is mixed to reduce the temperature inside the valve) to ensure no one is scolded by hot water above the required temperature.