"Once I drink the water, I feel it immediately," says Cameron Diaz. "I go from being a wilted plant to one that has been rejuvenated by the rain."

Cindy Crawford agrees: "Your body is so happy when you drink water." 

Your cardiologist is happy too.

Researchers from the Laboratory of Vascular and Matrix Genetics at the National Heart Lung and Blood Institute recently published a study in the European Heart Journal that shows drinking enough water to maintain properly diluted levels of sodium in your blood might reduce your risk of heart failure.

Looking at data on around 16,000 adults, they found that if you've got blood sodium levels above 142 mEq/L  (milliequivalents per liter) when you're age 45 to 66, you are more 39 percent more likely to develop left ventricular hypertrophy — a thickening of the wall of the heart's main pumping chamber — and heart failure during the next 25 years. That's a huge bump in your risk.

And every 1 mEq/L increase in your blood sodium levels from within the normal range of 135-146 mEq/L increases the likelihood of you developing heart failure by 5%.

How much water do you need?

Let your thirst be a guide, and that definitely changes depending on your activity level. Sweat more, drink more.

But the minimum is around 6-8 cups a day for women and 8-12 cups for men.

And avoid artificially sweetened and sugar/syrup-added beverages. Stick with water flavored with natural citrus and sugar-free electrolyte-restoring tablets.