The gradient of colorless -> yellow urine is based, among other factors, on the relative dilution of the excreted waste.
Increasing intake of water leads the kidneys to excrete more water for the same amount of excreted waste thereby diluting urine color
to be lighter "clearish". Vitamin intake also makes urine yellow. Please note, "clearish", vs cloudy, is a different issue with different causes.
Answer assisted by Rishi Kumar, Medical Student