The term 'water rights' refers to the right (formal or informal entitlement) of a user to use water from a water source, e.g., a river, stream, pond or source of groundwater. In areas with plentiful water and few users, such systems are generally not complicated or contentious. In other areas, especially arid areas where irrigation is practiced, such systems are often the source of conflict, both legal and physical. Some systems treat surface water and ground water in the same manner, while others use different principles for each.
Water rights are managed through water allocation regimes that determine levels of abstraction, manage licensing or other registration regimes for water users, and potentially create markets for the trade of water rights.