Posted By col The risks & hazards of burns/fires is a higher priorty than legionella. IF you want to test for legionella in the sprinkler tank then i am sure you will probably find it, and i am sure you will get a lot of emails telling you they know a company who will test it for you. the risk of legionella from a sprinkler system is only when in operation. And, during a fire I am sure I would be more worried about burning than catching legionella. Risks and hazards have to be put into proper context. No you cant turn a blind eye to it, yes you can do something about it. Do you need to clean the tank?? I certainly would think twice before dumping so much water, a) do you need to let the fire brigade know that you are dumping the water so that they can be in attendance. (i know that when one of the sites I have managed DID dump the water they had to inform the fire brigade and a fire tender had to be situated on site during the process otherwise the insurance on the site was void) b) do you need to inform the water authorities that you are ddischarging so much water down the drains at one time. Some companies do discharge the tanks and pay a fortune, others dose the system. I would recommend dosing the tank with silver peroxide checking it periodically (6 monthly). You have to remember that The risk of legionella is low during normal operating procedures.