A water system includes all the plant
The new rules are certainly clearer
equipment and installed components
in defining the responsibility
such as pipes, pumps, feedtanks,
of businesses when it comes to
showers, heat exchangers, quench
mitigating the risks of legionella
tanks, water softeners, chillers and
exposure. While at first this may
humidifiers to name just a few. These
seem daunting, with the right
kinds of setups are very conducive
help and use of control methods,
to stagnant water temperatures
businesses can not only comply
between 20-45 degrees Celsius in
with the law but also become
water sources, which can lead to spray
examples of best practice.
and legionella laden aerosols.
As a business, it's often easy to overlook
the fact that although the mains utility
has a responsibility to provide a bacteriafree water supply, once the mains supply
enters the building at the ball valve, even
small amounts of bacteria can quickly
multiply. Pipes under buildings and
facilities are often decades old, containing
rust, slime and microbiological films. These
are perfect environments for legionella to
thrive.
Stress free
Step by step
So what do you need to do to make sure
your system is not at risk? The first stage
is to establish whether your site is low risk
or not. If you're in a small building with no
water storage tanks, where the cold water
comes directly from the mains and hot
water is fed directly from instantaneous
or low volume water heaters at around 50
degrees Celsius, then there is very little
risk of exposure to individuals. Here, the
For many companies it can become a
nightmare to take control of this process.
Although temperature-based monitoring
is straightforward, many businesses
simply don't have the expertise to deal
with the more complex control methods
that include chemical dosing and water
treatment. Luckily, the regulations make
it permissible for businesses to appoint
a competent authority to manage the
assessment and control of legionella.
only source of risk is from toilets and hand
When it comes to water treatment, it's
washbasins.
important to select the right chemicals.
If you are low risk, you don't need to take
further control action. You simply need
to perform a regular risk assessment,
document the process, and review it when
changes are made to the system.
For businesses operating in anything
other than a small building, for example
if you're running a plant, the risk is much
higher. Facilities that have more complex
water systems need to create an asset
register; a schematic diagram of the
system highlighting deadlegs - lengths
of pipework where water can stagnate
- and identifying possible sources of
contamination as well as assessing current
Whether it's chlorine,
bromine or any oxidising
biocide, understanding
contact time, system
water-turnover rates and
half-life are essential in
developing a sustainable
long term treatment plan.
It's also more cost effective
to outsource the sitesurvey assessment and
monitoring to an expert
that really understands
how to keep your business
compliant.
disinfection and treatment methods.
Issue 20 PECM
79