One oft-repeated advice for beating back dehydration is to drink eight glasses of water a day. Well, that's a myth. Some of us need more or less, and how much you need changes day to day. Also, water isn't your only option. You can stay hydrated from many foods, too. Image by Exploring Photography (Suchitra).
As the US Centres for Disease Control and Prevention (CDC) notes:
...you can get some fluids through the foods that you eat. For example, broth soups and foods high in water content such as celery, tomatoes, or melons can contribute to fluid intake.
And frankly, you can find many foods that contain a lot of water. Vox outlines some of these in their article (linked below):
Their chart also includes foods that you wouldn't expect to be "hydrating", such as pasta, ice cream, hot dogs and pizza. But, dear reader, this isn't us telling you to substitute water with all of these foods and beverages to stay hydrated. After all, every one of these foods comes with added kilojoules (and a lot of them for some), where water is, by nature, kilojoule-free.
Plus, three-quarters of your body isn't made out of pizza. You still need water.