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 ****, 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.