Does my mother sin when she washes my grandmother more than necessary and wastes water, because my grandmother asks her to do so?

Question:
Honorable Shaykh, may Allah grant you success. The questioner says: My mother is the one who attends to my grandmother, who is her mother, and washes her when she needs it. But my grandmother asks her to wash her more than once, and she wastes water. So when my mother tells her that this is wastefulness, she gets angry and shouts at her. His question is: Does my mother sin when she wastes water while washing my grandmother?

Answer:
The one who washes her should not waste water. The one doing the washing should not waste water; she should take only what is needed. She washes her as much as is needed and does not waste water.