Multiple choice general knowledge science & technology What is the total water supply of the world? 302 million cubic miles 288 million cubic miles 326 million cubic miles 456 million cubic miles Reveal answer Fill a bubble to check yourself C Correct answer Explanation The total water supply on Earth is approximately 326 million cubic miles, covering about 71% of the planet's surface. This includes all oceans, seas, lakes, rivers, groundwater, and water in the atmosphere.