I would say it would be safer to keep it in the fridge. I studied microbiology in college. One bacteria, cell, can turn to billions, in just hours. Now the real question is, does kava make a good substrate, for consumption by bacteria? That variable, can make all the difference. I would say Kava tea made with water, would have a high PH. Bacteria, dose not like high PH. It tremendously slows down the cell division. If that's not the case, and Kava makes a good catalyst, for bacteria growth, then doing so, could cause problems with food poisoning. I doubt that's the case. But if made with milk, I would through it away. I threw some away the other day, because my wife made some with soy, and left it out all night. It turned into a big clump. Now if you want to be for sure its safe, you could pasteurize it. Keeping it at 140 degrees F. for 1 hour, will kill all the bad bacteria. Usually milk companies keep their's at 150, but 140 will work. Probably too much trouble. Much love. Roaddog....