Adequate Hydration Recommendations
Older women should drink at least 1.6 L of beverages daily, while older men should drink at least 2.0 L daily; for the general adult population, the European Food Safety Authority recommends 2.0 L/day total water intake for women and 2.5 L/day for men from all sources (beverages and food). 1, 2
General Population Guidelines
The most authoritative recommendations come from the European Food Safety Authority, which established adequate intake levels based on comprehensive review:
- Women: 2.0 L/day total water (from all sources including food), with at least 1.6 L from beverages 1, 2
- Men: 2.5 L/day total water (from all sources including food), with at least 2.0 L from beverages 1, 2
These recommendations account for the fact that beverages provide 70-80% of total fluid intake, with the remainder coming from food 1
Age-Specific Considerations
Older adults require special attention to hydration because thirst sensation diminishes with age and cannot be relied upon as the sole indicator of fluid needs 2. The 2019 ESPEN geriatrics guideline specifically mandates offering fluids regularly throughout the day rather than waiting for patients to request them 1
Adjustments for Increased Needs
Baseline recommendations must be increased under specific circumstances:
- Extreme temperatures: Hot weather significantly increases fluid requirements through increased perspiration 1
- Physical activity: Exercise substantially elevates water needs beyond baseline 1, 2
- Illness with fluid losses: Fever, diarrhea, vomiting, or hemorrhage require additional intake to compensate for excessive losses 1
- Athletes during travel: May require 2.0-2.5 L/day to prevent dehydration-related complications 1
Clinical Conditions Requiring Restriction
Heart failure and renal failure are the primary conditions necessitating fluid restriction rather than liberal intake 1. In these populations, the standard hydration recommendations do not apply and individualized limits must be established based on cardiac and renal function.
Practical Implementation
For healthy adults in temperate climates with sedentary lifestyles, these volumes represent minimum targets 2. Water should be the primary beverage consumed, though other non-caffeinated, non-alcoholic beverages contribute to total intake 2. The widespread "8 x 8" recommendation (eight 8-ounce glasses daily) lacks rigorous scientific support and is not based on systematic evidence 3.
Monitoring Adequacy
While thirst serves as an adequate guide for most healthy younger adults 2, relying solely on thirst is insufficient for older adults 2. Practical monitoring can include urine color (pale yellow indicates adequate hydration) and frequency (at least 4-6 times daily suggests sufficient intake) 2.