This prospective study was aimed at identifying the time of thirst above the recommended two hours after repeated information campaigns. Elective surgical patients ≥ 15 years of age were eligible to answer the questionnaire in four different periods between which information campaigns were carried out. A total of 765 patients were included. The median time of thirst was reduced from 6.5 hours to 3.0 hours (p < 0.0001) over a two-year period. Repeated interventions were found to be necessary to reduce the period of thirst to the recommended two hours for elective surgical patients.