I use a big *** soil pipe as my cooler, with a "t" piece at the bottom, I heard about the bacteria thing but had no idea it can cause legionaires disease!! how can i ensure i have no bacteria build ups? the thing is in the loft, i go up there each day to top it up, its been running for a few months now. I drained it out completly the other day, but the water looked clean! obviously that doesnt mean much!