Put some of it in the freezer, let ice form at the top, then skim it off. Methanol can contain up to 10% water and still burn in model engines just fine. It might even burn better in an overcompressed engine with additional water [to counteract detonation]. For the most part, fuel going "bad" is BS. Some nitro can evaporate, some water can collect, but most of the bad fuel claims are bogus, just like frequency hits are blamed for many crashes. I've used fuel that was left over in a vented model plane tank from a year before with no problems. It's easy to blame the fuel and it's easy to blame those stray radio waves, too. I mix my own with ingredients that I've had in drums for over 5 years, just use nitro, methanol and Klotz, don't need no steenking igniters.