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Appendix 3 – temperature regime

Table 1- Table of temperature control checks for control of legionella

Indicates the frequency that the temperatures of the hot and cold water system need to be monitored.

Frequency Check Cold water Hot water Notes
Monthly Sentinel taps The water temperature should be below 20°C after running the water for up to 2 minutes The water temperature should be at least 50°C within one minute of running the water. This check makes sure that the supply and return temperatures on each loop are unchanged i.e. the loop is functioning as required
If fitted to sentinel outlets, input to TMVs   The water supply to the TMV temperature should be at least 50°C within one minute of running the water One way of measuring this is to use a surface temperature probe
Water leaving and returning to calorifier   Outgoing water should be at least 60°C, return at least 50°C If fitted, the thermometer pocket at the top of the calorifier and on the return leg are useful points for accurate temperature measurement.  If installed, these measurements could be carried out and logged by a building management system
Six monthly Incoming cold water inlet (at least once in the winter and once in the summer) The water should preferably be below 20°C at all times   The most convenient place to measure is usually at the ball valve outlet to the cold water storage tank.
Annually Representative number of taps on a rotational basis The water temperature should be 20°C after running the water for two minutes The water temperature should be at least 50°C within one minute of running the water This check makes sure that the whole system is reaching satisfactory temperatures for legionella control

Table 2 - Checklist: hot and cold water services

Summarises the temperature and visual checks.

Service Task Frequency
Hot water services Arrange for samples to be taken from hot water calorifiers, in order to note condition of drain water As identified through risk assessment
Check flow and return temperatures at calorifiers are at least 60°C and 50°C respectively Monthly
Check the water has reached 50°C after running the water for up to one minute at the sentinel outlets Monthly
Visual check on internal surfaces of calorifiers for scale and sludge.  Check representative taps for temperature as above on a rotational basis Annually
Cold water services Check tank water temperatures remote from ball valve and mains temperature at ball valve.  Note maximum temperatures recorded by fixed max/min thermometer where fixed Six monthly
Check the water is below 20°C after running the water for up to 2 minutes in the sentinel outlets Monthly
Visually inspect cold water storage tanks and carry out remedial work where necessary. Check representative taps for temperature as above on a rotational basis Annually
Shower heads Dismantle, clean and descale shower heads and hoses Quarterly or as necessary
Little-used outlets Flush through and purge to drain, or purge to drain immediately before use, without release of aerosols Weekly
Bacterial analysis Samples should be taken from appropriate outlets and storage tanks / cylinders. These should be analysed by a competent company. Periodically (as identified through risk assessment)

* The tables show indicative frequencies derived from L8.

Updated2012-09-19