Are you getting enough water or too much?

Drink eight, 8 oz. glasses of water per day. You've heard this "rule" time and again, so you might be surprised to learn that, unlike many other foods and nutrients, there are no federal guidelines for how much water you should drink.

That's because body size, amount of physical activity, your medical conditions, the weather and diet can all affect your hydration needs. Furthermore, if you have certain health conditions–like kidney or heart disease–you may actually need to limit your intake.

Does how much water I drink really matter?

Your body needs water to perform some of its most essential jobs: regulating temperature, removing waste and supporting cell function throughout the body, just to name a few. Not drinking enough water hinders your body's ability to perform these basic functions and can lead to dehydration, a condition that causes a range of issues such as brain fog, digestive problems and even kidney stones.

How do I know if I'm drinking enough?

In most cases, you are safe drinking to thirst, say experts. In women, that should add up to about 91 oz. of water daily from all beverages and foods. For men, the amount would be about 125 oz., according to a report by the National Academy of Medicine. Here's what to keep in mind when setting a daily water intake goal:

• Add more for exercise. If you do any physical activity, like hiking, running, biking or swimming, your body needs more hydration, but don't go overboard.
• Food counts, too. Keep in mind that food can supply a lot of your daily water intake. A medium apple contains about 6 oz. of water.
• Choose the right foods. Many other fruits and veggies contain high amounts of water, too, including watermelon, lettuce, tomatoes and soup.

Is it possible to drink too much water?

Yes. Drinking past thirst can be hazardous to your health. Consuming large quantities of water can flood the kidneys, making them unable to process the liquid efficiently.

Those with kidney disease need to be especially careful of overconsumption.

People suffering from heart failure also need to watch their fluid intake because fluids build up in the body when the heart's pumping ability is weak. This can cause high blood pressure, swelling, weight gain and shortness of breath.

The bottom line: Drink when you're thirsty, and choose water over sugary juices or soda most of the time.