The waterflood method of improved oil recovery (IOR) and enhanced oil recovery (EOR) remains one of the most cost-effective and widely used means of enhancing hydrocarbon recovery from both conventional and unconventional reservoirs. To achieve the objective of improved and enhanced hydrocarbon recovery, the continual and steady injection of water by the surface waterflood system through injection wells into the reservoir at a specific rate and quality must be guaranteed. The injection system contains various subunits, units, equipment, subsystem and systems that operates seamlessly to ensure delivery of the required volume of water to either maintain the reservoir pressure and/or ensure adequate areal sweep efficiency of hydrocarbon for improved and enhanced oil recovery respectively. As the water flood system delivers water to the reservoir via injectors, certain components of the system may experience failure, resulting in the sudden, unplanned and abrupt shutdown, which may lead to several other failures in the injection wells and the reservoir. Hence, this study was conducted using quantitative reliability assessment technique on a case waterflood system using the Weibull and Duane models to analyse failure data obtained from the computerised maintenance management system (CMMS) of a floating, production, storage and offloading (FPSO) facility offshore Nigeria. From the Weibull and Duane failure statistical analysis of the waterflood systems, the η was 8836.61 h. The β was 1.6467, signifying the wear-out failure stage of the waterflood systems. Appropriate maintenance strategy, such as replacement, upgrading, or design-out of the waterflood system’s critical equipment were therefore recommended.