LEGIONELLA - World Health Organization

Table . Examples of values used as levels for correct ve act on for Leg onella n p ped
Country
The
Netherlands
United
Kingdom
water systems
Value
(CFU/l tre) Comment Reference
>1000 • Immediate action is needed to prevent
closure of (part of) system involved
100–1000 • Action depends on whether just one or
two or the majority of samples are positive;
review of control measures and risk
assessment required; possible disinfection
>1000 • Immediate review of control measures and
risk assessment required; possible disinfection
United States >10 000 • Prompt cleaning and/or biocide treatment
of the system
CFU = colony forming units
>100 000 • Immediate cleaning and/or biocide treatment;
take prompt steps to prevent employee exposure
VROM
(2002)
HSE
(2004)
OSAHD
(2005)
4.5.2 Establish documentation and communication procedures
Table 4.4 gives an example of documentation for monitoring and corrective action.
Table . Example of documentat on for mon tor ng and correct ve act on
Process
step Ind cator Mon tor ng
What Temperature
Heating
of water Temperature
How Thermometer
or thermocouple
data logger
Operat onal
l m ts Correct ve act ons
What Improve water
circulation and/or
increase water
temperature
Outlet:
Not less
than 65 ºC
Return:
Not less
than 63 ºC
How Add extra pump
on the return to
the water heater
Turn up thermostat
on calorifier
When Daily or online When Immediately
Where Return to water
heater and at
the outlet of the
heater
Who Building
engineer
Who Plumber
(for pump)
Building engineer
(for calorifier)
LEGIONELLA AND THE PREVENTION OF LEGIONELLOSIS