A pressure building regulator having a pressure receiving means in liquid communication with the liquid outlet passage, upon which a liquid in the liquid outlet passage can exert a balancing force, and a means for communicating the balancing force to the diaphragm opposing the backpressure force. The liquid pressure regulator typically employs a balancing piston which can transfer pressure fluctuations in the flow outlet into an equal and opposite force on the valve plug, and results in a net force of zero in the diaphragm plate. As a result, changes in the liquid pressure downstream of the valve plug only nominally, and typically negligibly, affect the upstream control of the liquid product. The pressure reducing regulator can be configured with a balancing piston which can transfer pressure fluctuations in the flow outlet into an equal and opposite force on the valve plug, and results in a net force of zero in the diaphragm plate. The liquid pressure regulator can have a differential diaphragm plate having a rigid structure, having a first side of a first surface area, and an opposed second side of a second surface area, where the first surface area and the second surface area are unequal. The differential diaphragm plate permits the use of conventional compressed air control regulators with the liquid pressure regulator to control a high pressure liquid system more accurately.