Polydipsia is a condition whereby individuals consume excessive amounts of liquids, which is common in patients with schizophrenia. A 17-item Polydipsia Screening Tool (PST; Copyright 2000 by Sheila Reynolds) was evaluated for psychometric properties. Five nurses and 70 psychiatric residents in a 92-bed nursing home comprised the samples. The interrater reliability (mean intraclass correlation coefficient) was 0.84. The average test-retest agreement was 92.4% with agreement ranging from 75% to 100%. Internal consistency of the tool was 0.79. Sensitivity and specificity were 80% and 68%, respectively. Additionally, validity of the PST was supported using a medical record history of polydipsia, low serum sodium, and low specific gravity.