Gainsville's treated waste water flows into the Trinity, where it then flows into Lake Ray Roberts, then flows into the Trinity, then flows into Lewisville Lake. Dallas pumps water from Lewisville Lake into treatment plants, then to customers. After the water is consumed, the sewage is sent to waste water treatment plants, and back into the Trinity to be used by communities DOWNSTREAM. This is the traditional process that for some bizarre reason you really really want to call "toilet to tap".
There, did I directly answer your question? Did I stick to the facts?
Here's another fun fact: the above outlined traditional process is not "toilet to tap" (which is simply a euphemism for the more accurate term of "water recycling"). Water recycling uses completely different infrastructure and technology, and implements a completely different resource flow. Ultimately, water recycling systems allow a community to re-use it's own waste water, instead of simply flushing it downstream - which is what Gainesville does to Dallas and ever other fucking municipality DOWNSTREAM from them.
There are no water recycling facilities on any part of the Trinity River watershed, so nobody that drinks water from the Trinity River or any reservoir fed from it is drinking "toilet to tap".
I've given you the definition you asked for three times now, and nobody is so stupid that they could fail to see any distinction between the systems in question. I'm guessing you suffer from some pathological need to be right coupled with low self esteem. When someone points out your mistakes, you feel intellectually threatened and react with childish denial. Kinda sad, really.