This paper reviews the field-scale water-injection experiences from the early Barkman and Davidson's water quality study in the 1970s to one of the latest Gulf of Mexico offshore field studies. It summarizes what petroleum engineers have learned during the past 30 years and provides a concise compendium to the current understanding of the water injectivity issue. Both onshore and offshore projects have been included and various water injection cases are presented, showing both successes are failures. The main objective of this paper is to help operators to develop operation and design strategies for current and future waterflooding projects.