A pump head for a fluid pump driven by a motor includes an inlet for receiving fluid at a first pressure and an outlet for outputting fluid at a second pressure greater than the first pressure. A relief valve cavity formed in the pump head housing includes a first portion in fluid communication with the inlet and a second portion in fluid communication with the outlet. A relief valve is disposed in the relief valve cavity with no portion of the relief positioned to block or otherwise impede the normal flow of fluid through the inlet or outlet. The relief valve is bi-directional and configured to operate in two modes including: (1) a low pressure relief mode where fluid flows from the inlet to the outlet when fluid pressure at the inlet exceeds fluid pressure at the outlet by a first threshold amount; and (2) a high pressure relief mode where fluid flows from the outlet to the inlet when fluid pressure at the outlet exceeds fluid pressure at the inlet by a second threshold amount greater than the first threshold amount. The relief valve cavity is specially configured to provide a barrier preventing an element of the relief valve from damaging the pump head in the event the relief valve element fails.