Additional Flush Phases
The only moving parts needed for a flush are the toilet handle, the flapper, the chain that connects them, and the water in the tank. All of the other mechanisms in the tank are designed to fill once it has been emptied by a flush. These fill mechanisms do not assist the flush in any way. The water pressure in the bowl has absolutely nothing to do with the water pressure in your house pipes.
The water pressure in the bowl is developed by the force of the water as it escapes from the toilet tank. Thus, good water pressure in your house has nothing to do with how well your toilet flushes. After the flush has drained the tank, the flapper, which is filled with air, closes. Once it has been raised by the flush handle the air within it keeps it open until the water level in the tank gets so low that it is insufficient to keep the flapper afloat or opened.
Float-Controlled Water Valve
With the flapper closed, the float-controlled water valve (ballcock) refills the tank. When the water rises the float to the proper level, it shuts off the ballcock and the tank is ready for the next flush. Like any other faucet in your home, the ballcock has a gasket that can fail and cause it to leak. When the float is in the up position, the ballcock should be off. If water runs with the float in the up position, chances are the ballcock needs to be adjusted or replaced.
A ballcock that is out of adjustment can cause the water level in the tank to increase and run out the overflow. If this happens, adjust the ballcock so that it shuts off when the water level is one-half to three-quarters of an inch below the top of the overflow tube. Also, if the refill tube from the inlet valve is pushed too far into the overflow pipe, a draining action will occur that will result in a leak.
When the Flapper Needs Attention
Finally, if the flapper or the seat it rests in are worn or out of alignment, a leak will result. Sometime this particular leak is almost impossible to detect. If you suspect this condition, try this test: put 10 drops of red food coloring in the toilet tank. Wait 60 minutes (do not flush) and check the bowl for color. If the food coloring got through, the flapper needs attention.