Is it possible to drink too much water in a day? and can drinking too much water in a day flush out the vitamins you took that day?

Over hydration: It is possible to drink too much water to the point of being dangerous to your health. The easiest way to avoid that is to monitor your urine. As long as it is a pale yellow you are likely drinking the right amount. If your urine looks clear you are probably drinking to much - the dander there is that you won't have enough electrolytes in your body (salts and minerals). You won't wash vitamins out