Sentinel tap temperature checks
Measure and log the temperature at a representative set of "sentinel" outlets each month — cold outlets should run below 20°C, hot outlets above 50°C (some guidance requires 55°C within a minute at the tap).
Measure and log the temperature at a representative set of "sentinel" outlets each month — cold outlets should run below 20°C, hot outlets above 50°C (some guidance requires 55°C within a minute at the tap).
Temperature is the main lever you have for controlling Legionella growth between full risk assessment reviews. A drifting reading at a sentinel point is the early warning that the system is set up wrong or a mixer valve has failed.
WHEN
Monthly, at the same set of sentinel outlets identified in your Legionella risk assessment.
COST
Free
indicative, checked 2026-08
WHO DOES IT
A document you write
LEGAL BASIS
HSE Approved Code of Practice L8 (Legionella), under the Health and Safety at Work etc. Act 1974.
Who this is for
Every venue.
What you’ll hold
- Sentinel tap temperature log
Watch out for
- Checking outlets close to the tank or cylinder instead of the sentinel points furthest from it, which are the ones most likely to show a problem.
- Running the tap for only a few seconds before measuring — let it run until the reading stabilises to get a true temperature.
- Not re-checking your list of sentinel outlets after a refit — new pipework can change which taps are actually representative.
Sources
- HSE — Legionnaires' disease checked 2026-09-02
See also
- Legionella risk assessment and control scheme— this becomes part of getting open →
- Flush little-used water outlets
This is item 39 of 60 in the free UK Compliance Calendar. See the whole list →