I would have thought there would be enough flow in most pipes to wash
out any eddies.
Only modern cases I've seen of Legionella were in a hospital I worked
in- hot water supply was scalding hot to prevent problems.
Unfortunately, the piping had been modified as the hospital grew. The
consequence was that the main hot water pipe had a bypass- a hot water
pipe had been taken off the supply then reattached at a seperate point
nearer the ward in question. This gave the water two different routes
to take- one was high resistance so very little (if any) bothered to go
that way. The consequential stasis in a moderately hot environment was
Legionella friendly, and this contaminated water was slowly "drip-fed"
back into the water supply near the ward. The ward in question was for
people with impaired immune systems and lung problems- and the main
water supply effected went straight to the showers.... Couldn't have
been worse really! IE people at risk from infection (lung infection
particularly) breathing in nebulised Legionella! Luckily the infection
was reasonably contained (though there were sadly deaths)... A
cautionary tale!!

Ben

BTW, most people think it's to do with infection whilst in the Foreign
Legion. Infact this is incorrect. It was first recognised in a hotel in
Phoenix, Arizona (and is also sometimes called Phoenix disease). It
was, however, recognised, amongst people visiting the hotel for a
convention of ex-members of the aforesaid Legion....

Merryterry wrote:
For all the 'Ostriches' that flamed me for an earlier posting on this
subject I would like to point them to this address.

http://www.wras.co.uk/PDF_Files/Info...ary%202006.pdf

The Health Protection Agency are investigating an unprecedented rise in
cases of legionella this autumn.