where does the water from the toilet come from
Flush toilet When a user flushes a toilet, a "toilet flapper valve" (not to be confused with a type of check valve) opens and allows water from a reservoir tank to quickly enter the toilet bowl. This rapid influx from the tank causes the swirling water in the bowl to rapidly rise and fill the U-shaped inverted siphon tube mounted in the back of the toilet. This full siphon tube starts the toilet's siphonic action. The siphon action quickly (4–7 seconds) “pulls” nearly all of the water and waste in the bowl and the on-rushing tank water down the drain—it flushes. When most of the water has drained out of the bowl, the continuous column of water up and over the bottom of the upside-down U-shaped drain pipe (the siphon) is broken when air enters the siphon tube. The toilet then gives its characteristic gurgle as the siphonic action ceases and no more water flows out of the toilet. After flushing, the flapper valve in the water tank closes; water lines and valves connected to the water supply refill the toilet tank and bowl. Then the toilet is again ready for use.