A toilet flush should either: - not drop the pressure of the cold water at all - drop both the hot and the cold equally (due to house input being limited) Th

A toilet flush should either: - not drop the pressure of the cold water at all - drop both the hot and the cold equally (due to house input being limited) The hot water is fed by the same input pressure as the cold, so they are the same pressure system. A temperature drop on a toilet flush is a pretty big fuckup by the plumber in the bathroom.