Yes, it is true that drinking too much water can whiten your eyes. Drinking lots of water can help to clear your body of toxins as well as to help you to produce tears that will prevent dry eye and redness. It is normal. Additionally, a blue eyeliner on the upper and bottom rims of your eyelids can help to make the whites of your eyes appear much whiter. Eye drops lead to make your eyes look bright and white again. Contacts can also artificially make your eyes look whiter and make sure you get lots of calcium and vitamin C in particular. Sleeping is one of the most important ways to make sure your eyes look white and healthy. While being lack of sleep is one of the quickest ways to make them look duller or blood-shot.
So far, i didn't see any proves that drinking water can make your eyes whiter. But everyone shall have be white in the eyes except the pupils. And if it comes to red or yellow, it is likely a sign of disease. For example, if it appear red, it may caused by eye infection, allergy or pink eyes. If it appear yellow, it may caused by liver problem. So, if you find your eyes are not white as most of people do, you'd better get a physical examination. Good luck.
It is not normal. Drinking suitable amount of water will make your eyes get moisture and make your eyes look bright. However too much amount of water will not make your eyes look whiter. The color of the eyes will change easily. If your eyes get whiter, you need to pay attention to it. You could drink some tea which may moisture your eyes because of the containing vitamin C.