The standard recommendation is around 11.5 cups for women (2.7 liters) and 15.5 cups for men (3.7 liters) of total fluid daily. But honestly about 20 percent of that comes from food so you don't need to chug that much plain water. The old 8 glasses rule is still decent if that is easy to remember.
Your actual needs depend on your body weight, activity level, climate and health. A basic rule is to take half your body weight in pounds and drink that many ounces of water. So if you weigh 140 pounds, aim for 70 ounces daily. Drink before meals to help with appetite control. Your pee should be pale yellow not dark.
If you are exercising or in hot weather drink more. Do not overhydrate at once because your kidneys can only process about 1 liter per hour.