This is an email I had from the hse dept some time back.
I looked at your link but could not find anything.
Hi Jeff,
Your query concerning legionella bacteria and window cleaning has come
through to me. You ask a number of questions in your message which may be
better talking through over the phone. However, I am out of the office for
two weeks beginning tomorrow so in case you don't pick this message up in
time, here are some of my thoughts regarding your questions:
"Can pure water incubate the Legionnaires' Disease?"
The answer here is that legionella will not tend to multiply to dangerous
levels in pure water because they need nutrients to grow and divide.
However, most water will contain some impurities that will act as a
nutrients source for legionella e.g., contamination in pipework - you'd
have to go to some lengths to ensure that water is totally uncontaminated.
"What precautions must window cleaners take to prevent Legionnaires'
disease?"
As well as nutrients, legionella bacteria require temperatures to fall
between 20C and 45C for them to grow and divide. Clearly in warm weather,
like we've had lately, there is potential for stored water to reach these
temperatures. Therefore the approach to take in order to control risks
from legionella would be one that took into account both cleanliness of
the system and water temperatures i.e.,
keep system (pipework, storage tanks, purification equipment) clean
if possible, take steps to keep stored water temperature below 20C.
I hope this has helped. I'll be in the office until about 4.30 today if
you wish to discuss this matter further with me (see number below).
Alternatively, you could talk to one of my colleagues by calling 1051 951
4831.
Regards,
Paul
Dr Paul J McDermott
HID SI4 (Biological Agents Unit)
0151 951 3405
Ref: AREL-6RLDHP