if u tap directly from supply then yes, when syabas out of water ur toilet also out of water
and no it will not automatically use water from tank
ill put up a diagram for u in a while



This post has been edited by ghuzzy: Feb 10 2015, 09:09 PM

here a better outlined diagram
but only one source of supply can be open at a time
if both open, u'll flood ur house


This post has been edited by ghuzzy: Feb 10 2015, 09:16 PM