Current practice is to describe the water requirements of riverine vegetation (usually as a dominant plant species) using a set of hydrological and hydraulic measures, collectively referred to as water regime. Water regime can be applied to any life-history stage but is generally limited to the two main stages: Maintenance (growth, persistence, reproduction of an already established plant) and Regeneration (germination, then establishment of new individuals). However, being based on statistical measures such as averages and ranges, water regime can be difficult to use predictively, as is needed when testing scenarios or setting priorities. A new way of describing water requirements based on inundation sequences and condition-states overcomes this limitation. A generic template in the form of a flow-chart comprises a series of condition-states (Good to Critical) arranged along two trajectories (Stress, Recovery). Each condition-state is defined in terms of severity of stress evident in the plant, and likelihood and ease of recovery; with recovery meaning persistence at that point in the landscape. One condition-state transitions to another, along a trajectory (or between trajectories), driven by the inundation sequence: and each transition has a specific inundation sequence. Vegetation or species water requirements are determined by fitting a species into this generic template. An understanding of its resistance and resilience characteristics are needed (physiological tolerances, propagule longevity, seed bank longevity) to fit the species or vegetation type into the template. Each of the transitions is then quantified, as best possible, drawing on published information, field observations, and consensus as appropriate. This new way of describing water requirements evolved as part of flow scenario modelling and has now been applied to a number of growth forms and vegetation types in the southern Murray-Darling Basin, such as Eleocharis acuta sedgelands, Vallisneria australis herblands and Black Box Eucalyptus largiflorens woodlands.