If I drink the water from my aquarium.?

Just monitor how you feel. If you don't show any obvious symptoms (nausea, vomiting, diarrhea, etc.) in the next day or so you should be fine. The threat from ingesting water from a fish tank stems from all of the micro-organisms that live in the water. If it was only a small amount of water, the acids in your stomach should be able to destroy the potential threats.