As long as no one has used the toilet without flushing, the water in the toilet is so clean you can drink it.
Actually, a toilet as a lot more cleaner than a work desk, keyboard, kitchen bench...you name it. Even your urine is drinkable as long as it's fresh and hot. In the old days, when they got hold on a bottle of liquor in the prisons, one person drank it, pissed it out and the next person drank the piss, pissed it out and and so on...since it still contained alcohol.
Somehow people immediately think about germs and **** when they hear the word "toilet", but there are far more scary things you put your hands and face in..all the time, everyday.