The amount of water an adult should drink per day can vary depending on various factors such as age, sex, weight, level of physical activity, and climate. However, a general guideline is to drink at least 8 cups (64 ounces) of water per day. This is equivalent to about 2 liters or half a gallon.
However, some health experts suggest that individuals may need more water, up to 3-4 liters per day, especially if they are physically active or live in hot and humid climates. It's also important to note that other sources of fluids, such as tea, coffee, and fruits, can also contribute to daily water intake.
Ultimately, it's important to listen to your body and drink enough water to stay hydrated and maintain optimal health. If you are unsure about how much water you should drink per day, consult with a healthcare professional.