You’ve got your skin-care routine down with serum, milky cleanser, and toner, but then without warning, your skin starts revolting: It’s dry, flaky, and irritated, and you have no idea why. This is not a problem that spares the famous folks of Tinseltown, either. Even dewy-skinned goddess Olivia Munn suffers from dry skin.

She told Byrdie that after moving to Green Bay, Wisconsin, a few years ago, she found a solution. No, not fancy products, but rather the most simple (and free) essential out there: H2O. Yep, plain old (non-lemon-infused) water.

“I think the biggest thing is I upped my water intake. You need water to look young and to lubricate your joints and your face.” —Olivia Munn

“I think the biggest thing is I upped my water intake. You need water to look young and to lubricate your joints and your face,” she says. “I do three liters a day, which is hard.” (And to minimize the daunting physical stature of giant one-liter bottles, Munn said she instead opts to drink from six smaller containers.)

Everyone knows about the basic keeps-you-alive properties of drinking water, but Munn claims imbibing so. much. water. did much more for her body. “Water helps kick up your metabolism [and] helps you keep weight off,” she said, adding that you can even take things a step further with a strategic selection of vitamins and hyaluronic acid, which she said is vital “to help carry that water to your skin.”

But as a general rule of thumb, according to some nutritionists, the amount of water you drink every day should be based on your body weight: Divide your weight in half, and that’s how much you should aim to down in ounces.

Already sipped your daily hydration quota? There are other skin-saving hacks like jade rollers, brightening sheet masks, and self-cleaning towels to try.

Olivia Munn also wants you to consider freezing your eggs and the 80/20 diet.

This story was originally published on December 19, 2017; it was updated on June 27, 2018.