I don't use water because I don't like the extra clean up. Several overnight smokes on my 22.5 wsm. Fill with unlit to the brim and I add about 10 fully lit to that. assemble the smoker, add the meat, wait till the temp settles in around where I want it and go to sleep. the maverick is in the living room because I aint getting up anyway because I don't care to loose sleep. When I do get up, when I want to, the temp is always close to what I wanted. Now I don't know the temperature fluctuations that took place overnight but the meat always turns out fine but based on what I observe on my daytime cooks the fluctuations are minimal anyway. Just cook, don't worry and have fun.