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Posted By Carsten Barrett
Looking for some help on above.
Our Client requires us to have a Legionella Risk Assessment.
Common sense tells me we don't have any issues. We have several Portacabins and Toilets plumbed in we have a sink with hot & cold water - no showers!
Legionella is not an area of expertise, I need to know what to cite on the RA.
Help please
CB
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Posted By David Matthew
Do you have any water storage tanks including cisterns and what temperature does the water from the hot tap come out at?
I'm not an expert nor do I currently have the guidance notes with me but from memory legionella thrives in water with a temperature between 20-60 degrees C so heated water must reach a certain temperature within a minute of turning the tap on I think - I'm sure other will correct me if I'm wrong or provide more narrative.
Things to look out for are dead legs where water can stagnate and legionella multiply, storage tank with a film on top of them which provides nutrients for the bacteria to grow, overflow pipe taht don't have a mesh over the end of them allowing flies etc to get into the tanks/ cisterns etc.
I believe that the population at risk tends to be the old and the very young and people with a suppressed immune system.
Hope this helps,
regards,
David
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Posted By Adrian Watson
Legionella needs organic material, bio film, time (5 days at 25 C) , and a temperature range between 25 and 45 C to multiply. To cause infection it must be inhaled by a susceptible person.
Regards Adrian
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Posted By Jeff Manion
If you store water (cold or hot) in something other than the rising water mains services pipes, you have a low risk.
Risk is increased due to storage in tanks / vessels / cylinders.
These things should be managed by checks and inspections, long breaks - Easter or similar, flush water - if considered necessary.
From your information, therefore mains water, no storage equals low risk.
JM
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Posted By John A Wright
Jeff, can you run that by again. You said
>>If you store water (cold or hot) in something other than the rising water mains services pipes, you have a low risk.
Then you said
>>mains water, no storage equals low risk.
So they are both low risk???
:0)
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Posted By Adrian Watson
For legionella to grow you need legionella sp, nutrients (organic materials, cysteine & iron), harbourage (bio-film inc protozoa), time and temperature. To get infected you need an aerosol and thousands of organisms.
Normal domestic systems and general plumbing systems are low risk. In this case, you have no risk as you do not have an inhalable aerosol.
The estimated annual risk of legionellosis from domestic size systems is in the order of 1 in 5,000,000.
Regards Adrian Watson
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Posted By holmezy
While we are on about legionella.....
My service provider, who shall remain nameless, always tries to convince me that a flushing toilet is a medium to high risk. We have 2 flushing toilets, one from stored water, the other from mains, yet he sees no differential in risk. All of the bug counts are ok from the tank, and all temperatures are either cold enough or hot enough, yet he tells me the aerosol produced by the toilet is whafted around by the opening and closing of the cubicle door. I, personally, see little or no risk in either and am certainly not in the habit of sniffing toilet systems whilst at knee height!
Is it just me, or have others had the same?
Holmezy
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Posted By Jeff Manion
Water in mains fed (on-line) water is of low risk as generally the water is pre-chlorinated at source. The risk "may" increase when exiting ball valve and mixes with air, but if the tank is clean and clear and not stagnated low risk.
What we as man (or woman etc etc) do with plumbing - alters the risk, some just make adjustments without any consideration / knowledge.
It is mentioned that bug counts are okay, okay compared to what, normally bugs counts are checked against drinking water quality, so you may discount the issue.
As for the aerosol, if you flush, you leave, risk is low, but low compared to legionella or what?
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