The current global area equipped for irrigation provides 30-40% of the world's gross food output. Water used for plant irrigation may harbour plant pathogens and foster their spread. This represents a serious risk for crop health, with heavy socio-economic consequences. More specifically to plant pathogenic bacteria (PPB), a range of species have been reported from irrigation systems and their potential role in epidemic development has long been recognized. However, only a few studies have been performed to date on the ecology of PPB in the context of water habitats. Consequently, current knowledge of the biology, ecology and epidemiology of PPB in irrigation water is poor. In light of this, an attempt is made to describe the most relevant information concerning the role of open irrigation systems in the survival and dissemination of PPB throughout the range of cultivations and the possible consequences for crop health. The information described in this paper will help to improve understanding on the overlooked role of irrigation water as a reservoir of PPB.