What temperature should the hot water be?
Household hot water
Hot water should be stored in the hot water cylinder at a minimum temperature of 60ºC to avoid the growth of Legionella bacteria, but for safety reasons water in the bathroom basin, bath or shower should be below a maximum of 55ºC.
The following chart shows how dangerous hot water can be to the tender skin of children and the elderly, so weigh up the cost of improvements to your hot water system against the cost of serious burns.
Temperature of water Time to cause a bad burn
66º C (150º F) 2 seconds
60º C (140º F) 6 seconds
52º C (125º F) 2 minutes
49º C (120º F) 10 minutes
To reduce the temperature between the hot water cylinder (60º C) and the bathroom (ideally, 52º C or less) it is a good idea to have a tempering valve fitted between the two. As the hot water leaves the cylinder, the valve mixes cold water in, thus reducing the temperature. Another option is to install taps and shower mixers that have a tempering capability.
To adjust the temperature in your hot water cylinder, see 'Adjusting the temperature of the hot water' under 'Electrical management and repairs' in this website.
The temperature of in-line gas hot water can be adjusted on the wall monitor.
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