Once gold medalist Michael Phelps was in training, he was up to his neck in water and seemed to leave his self-destructive habits behind.

Could it be that there's something about water that's just plain health-inducing?

Making an ample supply of water available to school kids sure seems to clean up their bad habits — at least when it comes to calorie consumption from sodas and sweet juices.

In 2009, New York City installed electrically cooled, clear jugs that dispense water quickly in 39 percent of the 1,227 public elementary and middle schools across the city.

According to a new study, it tripled kids' water consumption, and contributed to a 9.5 percent decrease in severe obesity and a 5.5 percent drop in obesity in grades K-8.

Here's how you and your child can stay well-hydrated, and shed a few pounds.

Rule 1: Check urine. Clear/pale, straw-colored urine signals good hydration. Darker? Drink more water.

Rule 2: Active adults need 16 to 20 ounces of water one to two hours before activity; 6-12 ounces for every 15 minutes outside; afterward, 12 to 24 ounces more. Exercising for more than an hour? Hydrate with a drink that provides sodium and potassium.

Rule 3: Eating lots of fruits and vegetables can supply 20 percent of your hydration needs.

Rule 4: A 2015 study found that 50 percent of U.S. kids are low on hydration; 25 percent drank no plain water at all. Kids 4 to 8 need 5 cups of water a day; girls 9 to 13 need 7 cups, boys need 8.

Drink up!