A legionella temperature log is the monthly record that a building's water is being kept too hot or too cold for Legionella bacteria to thrive. Most written schemes of control in the UK ask for the same round each month: read the sentinel outlets nearest to and furthest from the hot water source and the cold tank, read a rotating sample of other outlets, check the calorifier, and flush anything that has not been used. This template records that round outlet by outlet, with the actual readings in °C, and turns every reading that missed its target into a finding with an action against it. Fill it in here and download the PDF without an account, or speak while you walk, and the document writes itself.
What the log is for
In the UK, the Health and Safety Executive's Approved Code of Practice L8 and its technical guidance HSG274 describe how a duty holder keeps legionella risk under control. The risk assessment identifies the risks; the written scheme sets out the checks that control them and how often; the log is the evidence that those checks were actually done. An inspector, an insurer or a client asking about water safety will usually want to see all three.
This form records the checks the written scheme requires. It does not replace the scheme or the assessment, and filling it in does not make a building compliant on its own — it shows what was measured, when, by whom, and what was done when a number was wrong.
Sentinel and rotational outlets
Sentinel outlets are the fixed points that tell you whether the whole system is behaving: on a hot water circuit, usually the outlets closest to and farthest from the calorifier or heater; on a cold system, the outlets closest to and farthest from the storage tank or incoming main. They are read every month. Rotational outlets are the rest, read a few at a time so that every outlet in the building gets looked at over a cycle the scheme sets.
Outlets go into this form as a list. Give each one the reference used on the scheme's drawing or asset register, so next month's reading lines up with this month's.
Taking a reading
Run the hot side for a minute and the cold side for two, then hold the probe in the running water and record the figure. Write the number down rather than a tick — a reading that is creeping towards its limit is only visible if the numbers are there to compare.
Where an outlet is fed through a thermostatic mixing valve (TMV), the mixed water is meant to sit below the temperature that protects against legionella, to protect people from scalding. Record the mixed reading separately, and note that the TMV itself usually has its own servicing routine.
When a reading misses
Mark the outlet as not within target and the form opens an action for it: what you did on the spot, the re-test reading, who owns the next step and by when. Flushing and re-testing often settles it; a hot outlet that stays cool, or a cold outlet that stays warm, usually points to something in the system — a failing pump, a valve, a calorifier set too low, pipework running through a warm space — and should go to the responsible person named in the scheme.
Common questions
How often should legionella temperature checks be done?
Most written schemes ask for sentinel outlets to be read monthly, with other outlets read on a rotation and calorifiers checked at a set interval. Follow the frequencies in your own written scheme, which your risk assessment should have set for that building.
What temperatures should the outlets reach?
Use the targets in your written scheme. Commonly cited figures are hot water reaching at least 50 °C within a minute (55 °C in healthcare settings) and cold water below 20 °C within two minutes, with calorifiers commonly storing at 60 °C and returning at 50 °C or above. Mixed water from a TMV is set lower, to a range chosen for the people using it.
What is a sentinel outlet?
A fixed outlet chosen because it shows how the whole circuit is behaving — usually the first and last on a hot or cold run. If the sentinels are within target, the outlets between them are likely to be too.
Who can take the readings?
Anyone the duty holder has trained to do it and named in the written scheme — often a caretaker, site manager or water hygiene contractor. The responsible person should review the log and act on anything out of range.
Is this an official HSE form?
No. HSE does not issue a standard log. This template records the readings and actions a written scheme typically asks for, in a form you can keep, compare month to month and hand over when asked.