A diaphragm sealed, pressure balanced valve assembly includes a valve body and a cartridge connected to the valve body. The cartridge includes a cartridge loading end having a retaining member engaged to the cartridge loading end. A valve member slides coaxial to a longitudinal axis of the valve body. A resilient material first diaphragm is connected to and extends diametrically outward from the valve member having a diaphragm body clasped between the retaining member and the cartridge loading end, creating a first diaphragm fluid pressure boundary. A resilient material second diaphragm is connected to and extends diametrically outward from the valve member at an opposite end of the valve member with respect to the first diaphragm and has a diaphragm body clasped between first and second adjustable retention members, creating a second diaphragm fluid pressure boundary.