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PLUMBING CONNECTION
SPRING 2016
Plumbing Connection would like to thank the team at Enware
for their contribution to this article.
References
(1)
Paszko-Kolva, C., Shahmat, M., Keiser, J. and Colwell, R.R. (1993)
Prevalence of antibodies against Legionella species in healthy and
patient populations.
(2)
Makin, T. (2010) “Venturi system could be major breakthrough”,
Health Estate Journal April 2010.
(3)
Lin, Y, E. (2013) “Reducing Legionella Infection in Hospitals by
Risk Assessment and Cost-Effective Preventative Measures”, RID
Newsletter October 2013.
(4)
Arvand, M. (2011) Contamination of the cold water distribution
system of health care facilities by Legionella pneumophila: Do we
know the true dimension?
For safe delivery, thermostatic mixing valves which mix hot
and cold water at the point of use should be used.
BENCHMARKING HYDRAULIC DESIGN
While internal water systems in Australia have
traditionally been designed with issues such as Legionella
control in mind, inconsistency differences between the
minimal design guidelines of the various States and other
regulatory bodies’ means conflicts can occur. The ongoing
threat of Legionnaire’s Disease is a very real one and
therefore something must be addressed by the building,
design and plumbing sectors.
Thankfully we are blessed with hindsight and can
look to European models that are leading the way in the
management of Legionella in hospitals. The UK Department
of Health provides comprehensive advice and guidance in a
code of practice for the control of Legionella in health water
systems, namely the temperatures at which water should be
maintained at throughout a hospital’s water supply system.
These practices are focussed around distributing water hot
at all times therefore requiring a thermostatic mixing valve
for safe warm water delivery avoiding potential scalding
risks.
Ideally for safe water delivery and to minimise microbial
growth risks in plumbing systems, thermostatic mixing
valves which mix hot and cold water at the point of use
should be used. By integrating the thermostatic mixer into
a point-of-use mixer, the risk of Legionella is minimised as
full temperature heated water is plumbed directly to the
draw off fixture eliminating warm water pipe lines where
Legionella may breed.
WHAT CAN BE DONE
A number of measures can be employed to control
Legionella bacteria in hot and cold potable water systems.
∫ High and Low temperatures (>50 at hot water distribution
outlets and <20 at cold water outlets).
∫ Anti-bacterial water treatment regimes (Chlorine dioxide,
copper and silver ions, silver and hydrogen perozide, UV,
ozone etc).
∫ Regular flushing of outlets, or purging of them
immediately prior to use – without generating aerosols.
∫ Point of use filtration.
∫ Regular monitoring of the water distribution system.
Legionella site positivity and control measures need to be
routinely monitored for the life of the system.
∫ Water storage should be kept to the safest minimum.
∫ Water velocities within the pipes should be increased for
improved water movement.
∫ All pipework should be lagged and wherever possible, cold
pipes separated from heat sources.
∫ For safe delivery, thermostatic mixing valves which mix
hot and cold water at the point of use should be used to
ensure the water can be kept hot for as long as possible
without the risk of scalding.
When was the last time you tested a client’s health facility
water system for Legionella?
LEGIONELLA