The key temperatures
- Hot water stored in a calorifier or cylinder: 60°C or above
- Calorifier return: 50°C or above (55°C in healthcare)
- Hot water at outlets: at least 50°C within one minute (55°C in healthcare)
- Cold water at outlets: below 20°C within two minutes
What are sentinel outlets?
Sentinel outlets are the taps nearest to and furthest from the hot water source or cold water tank on each loop. If the sentinels are at the right temperature, the rest of the loop is likely to be too. They are usually checked monthly.
How to take a reading
Use a calibrated digital thermometer with a suitable probe. Run the outlet and record the temperature at the time stated in your scheme, usually one minute for hot and two minutes for cold. Record the outlet, time, temperature and who took it.
What if the readings are wrong?
Investigate the cause: thermostat settings, poor insulation, long dead legs, failed circulation pumps or heat gain in cold pipework. Fix the cause, re-check and record what you did.
Frequently asked questions
Why is 20°C the limit for cold water?
Legionella starts to multiply above about 20°C, so keeping cold water below that limits growth.
Disclaimer: This guide is general information about UK requirements and is not legal advice. Always check the current legislation and guidance for your premises.