Hi hive mind, have any of you got natural water fed polytunnels or greenhouses? If so what controls you have considered / have in place for management of legionella risk? 

I have a polytunnel with reed seed trays in - we use natural water from a nearby reedbed to water them.  We currently pump water into a storage containers and then hose pipe it into the seed trays. 

The polytunnel is usually hot and humid, great for legionella and reeds alike. I am assuming there is legionella bacteria in the water source and that the conditions i give it in the poly tunnel will allow it to grow, therefore i need to control the risks for anyone working inside

Ideas and your experiences welcome :-)

You can't control uncertainty and you should never work on assumption.

Get a professional in and determine if their is a problem which requires control.

A report by a competent person referencing samples taken across site will give the direction for what, if anything, needs doing.

Legionella is very common in natural water sources - a one off test would be irrelevant as it could change on a dayly basis. Its not clear from your email if you understand the other conditions that need to be present for it to be a hazard or what range of controls you could consider.

I have advised on greenhouse and politunnels in the past - they are all different, to say what i had done in these could be very dangerouse as we know nothing about the other factors in your workplace. Im afraid I am going to have to agree with my collegue - its sounds as if you need to bring in a compitant advisor not just ask on here for help.