Quick Answer
Water does not use the same grams-to-cups value as every other ingredient. Using a practical US cup reference, 237 grams of water is about 1 cup.
That means 100 grams of water is about 0.42 cups, while 200 grams is about 0.84 cups.
Water is the standard reference for density. One US cup of water is approximately 237 grams, making it a reliable baseline for conversions.