Fluid needs vary based on factors like age, sex, activity level, and overall health. For example, pregnant and breastfeeding mothers have higher water needs, while people with certain medical diagnoses like renal or heart disease have totally different fluid needs.
The AI (adequate intake) for water consumption has been determined for overall generally healthy people based on age and sex.
According to the Academy of Nutrition Dietetics, that looks like:
11.5 cups per day for women, and for men about 15.5 cups. These estimates, however, include fluids consumed from both foods and beverages, including water. You typically get about 20% of the water you need from the food you eat.