Here's why:

* Earth is a planet made of rock and metal. Water is a liquid that exists on the surface. It's impossible to flood the entire planet to the point of destroying it.

* The water cycle ensures balance. Water evaporates, forms clouds, and falls back as rain or snow, constantly recycling itself. This natural process prevents a catastrophic water buildup.

* The Earth's gravity holds everything in place. Even if a massive amount of water somehow appeared, it would be held to the Earth's surface by gravity.

However, the idea of a "water apocalypse" is a popular theme in fiction, exploring the potential consequences of massive floods or rising sea levels. These stories often serve as warnings about environmental damage and the need for sustainable practices.

It's crucial to remember that the Earth is a complex and resilient system, and catastrophic events like a complete water-based destruction are not scientifically plausible.