Purpose: The purpose of the study was to examine preventive effects of tailored water drinking on orthostatic hypotension and heart rate variability in the elderly. Methods: A non-equivalent control group pre and post time-series design was adapted. Among a total of 64 elderly people admitted to two nursing homes, 35 elderly were assigned to the experimental group and 29 were assigned to the control group. As for the elderly people in the experimental group, tailed water drink was provided according to the scheduled time for six weeks. Blood pressure and heart rate were measured twice before the intervention in both groups. The data were analyzed with SPSS program using t-test, ${chi}^2$-test, and repeated measure of ANOVA. Results: There were significant differences in blood pressure and heart rate variability between the two groups. Conclusion: Tailored water drinking had preventive effects on decreasing blood pressure fall as well as prevalence of orthostatic hypotension in the elderly people.