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A practical guide to checking water temperatures to minimise the risk of legionellosis

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Under the Health and Safety Act and the COSHH (control of substances hazardous to health) regulations, schools and academies are legally obliged to record water temperatures on a monthly basis.

Here is a specific guide to taking and recording water temperatures in a manner that is compliant with the approved code of practice.

Every month the temperature from the school’s hot taps needs to be checked and recorded. This can be done in rotation, choosing a different start point, or sentinel tap, each time.

  • Start with the tap at the furthest point from the boiler. This will be known as the ‘sentinel tap’
  • Turn on the sentinel tap
  • Hold the thermometer under the hot tap for one minute
  • The temperature should have reached at least 50ºC
  • Note and record the actual temperature reached
  • If the temperature is below 50ºC advise the bursar/site manager who will instigate the necessary remedial action

NB. Mixer or blender valves ensure water temperatures at the outlet do not exceed 45 degrees centigrade. Where such valves are fitted the temperature of the hot water should therefore be checked at the calorifier outlet, and should be at least 60 degrees centigrade at that point.

Also required is a monthly record of the temperatures being achieved by the boiler or calorifier.

  • Identify the temperature gauges on the calorifier
  • Take and record the temperature of the flow from the calorifier
  • Take and record the temperature of the return to the calorifier
  • The flow temperature from the calorifier should exceed 60ºC
  • If the flow temperature is below 60ºC advise the bursar/site manager who will instigate the necessary remedial action

To ensure the cold water temperatures are posing no risk of bacterial proliferation the cold water outlets must be checked monthly as well.

  • Identify a programme to check the temperature at each cold water outlet on a rotational basis
  • Allow the sentinel tap to run for up to two minutes with the thermometer in the water flow
  • The temperature should not exceed 20ºC
  • Note and record the actual temperature
  • If the cold water temperature exceeds 20ºC advise the bursar/site manager who will instigate remedial action

Every six months a record needs to be taken of the water temperature in the cold water storage tank. This can be achieved as follows:

  • Identify location of cold water storage tanks
  • Ensure that access does not constitute a health and safety risk
  • Remove tank lid
  • Check the water temperature remote from the ball valve, record the temperature
  • Check the temperature of the mains water entering the tank from the mains, record the temperature
  • If fitted record the minimum and maximum temperatures registered on min/max thermometer
  • Replace the tank lids

All temperature records should include:

  • The  location of the outlet or tank
  • The actual temperature
  • Who carried out the check
  • Date and time of the check
  • Any issues identified
  • Action taken

If you have any questions regarding legionellosis please contact the NAHT property support team on 0845 519 7001 or email helpdesk@nahtassure.co.uk.


Page Published: 27/01/2015