The aim of this study was to identify the best prognostic parameters for quickly assessing fluid volume status in the context of nutritional status and water balance in older persons and to facilitate decision-making of the general practitioner (GP). This pilot study was conducted with 142 volunteers aged 60 years or older who were Polish students of the University of the Third Age. Inclusion and exclusion criteria for the study were defined. Assessment tools included: the Mini Nutritional Assessment questionnaire (MNA®) and the anthropometric measurements. Weight and body composition analysis were determined by Bioelectrical Impedance Analysis (BIA) using the Tanita MC-780 multi frequency segmental Body Composition Analyzer. According to the MNA scale, 89.2% of the sample was wellnourished and 10.8% were at risk of malnutrition. A total of 47.1% participants had normal body mass index, 20.6% were overweight, and 32.3% were obese. The BIA showed that females had more fat mass (FM) compared to males (35.84% vs 23.90%), while men had more free fat mass (FFM) and total body water (TBW; 61.16% vs 45.22% and 53.31% vs 45.22%respectively). There were no statistically significant differences in FM, FFM, and TBW by age. The ratio of Extracellular to Total Body Water (ECW/TBW) was higher in women than in men (46.76% vs 43.66%). Of all measures, only ECW/TBW increased significantly with age and sex, especially after 65 years. We propose that ECW/TBW may be used as the first, simple, and fast indicator of water volume status in the context of nutritional status and water balance in older subjects. Systematic control of the ECW/TBW by GP or nurse may increase senior independence, resulting in longer self-maintenance at home and reduced hospital admissions.