I have a "new to me" bourbon barrel. It's 10 gallons and was drained 3/4 months ago. The distiller said he filled it with 2 liters of R.O. water to keep it sealed. I was wondering what if anything I need to do to prep a barrel in the situation? Do I sanitize with a potassium metabisulphite solution? Boiling water? A large bottle of whiskey/bourbon? All have been suggested, but does anyone know for sure?