Legionella Monitoring and Routine Inspection -
Review of Control Measures
Part 8 of the HSE's Approved Code of Practice "Legionnaires'
disease: The control of legionella bacteria in water systems"
Review of control measures – monitoring and routine
inspection
61 - If precautions are to remain effective,
the condition and performance of the system will need to be monitored.
This should be the responsibility of the responsible person or,
where appropriate, an external contractor or an independent third
party and should involve:
(a) checking the performance of the
system and its component parts;
(b) inspecting the accessible parts
of the system for damage and signs of contamination; and
(c) monitoring to ensure that the treatment
regime continues to control to the required standard.
62 - The frequency and extent of routine monitoring
will depend on the operating characteristics of the system, but
should be at least weekly.
63 - Testing of water quality is an essential
part of the treatment regime, particularly in cooling towers.
It may be carried out by a service provider, such as a water treatment
company or consultant, or by the operator, provided they have
been trained to do so and are properly supervised. The type of
tests required will depend on the nature of the system and further
details are given in Part 2 for both cooling towers and hot and
cold water systems.
64 - The routine monitoring of general bacterial
numbers (total viable count) is also appropriate as an indication
of whether microbiological control is being achieved. This is
generally only carried out for cooling towers, rather than hot
and cold water systems. Periodic sampling and testing for the
presence of legionella bacteria may also be relevant to show that
adequate control is being achieved. However, reliably detecting
the presence of legionella bacteria is technically difficult and
requires specialist laboratory facilities. The interpretation
of results is also difficult; a negative result is no guarantee
that legionella bacteria are not present. Conversely, a positive
result may not indicate a failure of controls as legionella are
present in almost all natural water sources. Further guidance
on bacteriological monitoring and interpretation of test results
can be found in Part 2.
65 - The results of monitoring and testing should
be interpreted by a suitably experienced and competent person
and any remedial measures, where necessary, should be carried
out promptly.
Extracted from "Approved Code of Practice (ACoP)
and Guidance "Legionnaires' disease: The control of legionella
bacteria in water systems" (L8)" © Crown copyright
This document is continued in the next issue of Accepta's newsletter
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