An adult's daily water intake varies depending on factors like sex, activity level, climate, and health status. General guidelines from reputable sources are:
- Men typically need about 15.5 cups (3.7 liters) of fluids per day.
- Women typically need about 11.5 cups (2.7 liters) of fluids per day.
These amounts include all fluids consumed, not just plain water, and also account for water content in foods
. Other recommendations suggest:
- The NHS advises 6 to 8 cups (about 1.5 to 2 liters) of fluid daily for most adults
- The National Academy of Medicine recommends about 13 cups (104 ounces) for men and 9 cups (72 ounces) for women daily, with adjustments for pregnancy and breastfeeding
- The British Dietetic Association suggests about 2 liters (8 cups) for women and 2 liters for men, with increases for pregnancy or breastfeeding
Factors increasing water needs include:
- Physical activity or exercise (due to sweat loss)
- Hot or humid weather
- Higher altitudes
- Pregnancy and breastfeeding
- Illnesses causing fluid loss (fever, vomiting, diarrhea)
The common "8 glasses a day" rule (about 2 liters) is a simple guideline but may be insufficient for many adults, especially men or active individuals
. In summary, a healthy adult man should aim for about 3.7 liters (15.5 cups) of fluids daily, and a healthy adult woman about 2.7 liters (11.5 cups), adjusting intake based on personal factors and thirst cues
