Why did Khushi tell Rupa to "drink plenty of water in future"? (Higher-order thinking)

Khushi wakes up hearing birds chirping.

Khushi went to Kushumpur to visit (her grandfather's home. She was happy because it was a lovely morning and she got to see trees, paddy fields and butterflies on the way.

Khushi is happy because she will go to her grandfather's home. There she will meet with her friends.

I should brush my teeth after breakfast and dinner. I should take my bath everyday. Also I must drink plenty of pure water.

Pure water keeps my body fit and healthy. It helps me to get free from stomach pain.

Khushi saw many trees, golden paddy field, blue sky on her way to Kusumpur.