I am just thinking of residue that might be in the barrel,,, even with food grade there was something in the barrel at one point,,,, I would pour a couple gallons of bleach in it slosh it around then drain it and put it out in the sun to dry,,,, it probably wouldn't hurt to make a call to a plant that bottles distilled water,,, they could say it will be just fine the way it isI never thought of that. I was planing on pouring the distilled water in to the barrel. The barrel that I have is a food grade barrel. In the past I used it for drinking water in the fur shed.