Pressure reducing valves (also called PRV's), are compact, inexpensive devices that perform two functions: (1) they automatically reduce the high incoming
water pressure from the city mains to provide a lower,
more functional pressure for distribution in the home;
(2) they "regulate" by maintaining a set pressure in the
home usually 50 psi -- thereby insuring that the home
piping and appliances operate under a safe, more
moderate, but satisfactory pressure.