Minimum Temperatures for Domestic Hot Water
Domestic Hot Water
Domestic Hot Water
- Temperature in the Distribution System
≥ 55°C at all hot water outlets throughout the distribution network.
This is an essential requirement to prevent the growth of Legionella bacteria.
- Temperature at the Source (Boiler or Storage Tank)
A minimum of 60°C is recommended for domestic hot water production.
This compensates for heat losses within the pipework and ensures that at least 55°C is maintained at the outlets.
- Instantaneous Water Heaters and Combination Boilers
These systems must be capable of delivering at least 55°C at the outlet.
Why Are These Temperatures Important?
Legionella bacteria thrive between 25°C and 50°C.
Above 55°C, bacterial growth is significantly reduced.
At 60°C, Legionella gradually dies off.
Practical Recommendations
- Maintain storage tanks permanently at 60°C.
- Ensure circulation pipes never fall below 55°C.
- Avoid dead-end pipe sections and stagnant water.
- Flush infrequently used outlets on a weekly basis.
- Hot Water Delivery Time
A temperature of 40°C reached within 10 to 15 seconds is generally considered acceptable.
If it takes more than 30 seconds to reach this temperature, the level of comfort is considered insufficient under NBN EN 806-2.
