I have drank water (or apple juice) up to maybe 2 or 3 hours before the first ES drink and had no problems. My husband did the same thing last night and all worked out OK. But I read where someone drank water right around the same time as their OO (Olive-Oil) mix and were really sick in the middle of the night, so I'd make I didn't drink it then. You'll just have to see how you react.