How is rain water better than tap water for GRASS

please tell me truthful knowledge and tell me a place where u can talk with science test online

Rain water is pure water with oxygenation from falling thru the air. There also is a little bit of nutrients from the dust it collects as it falls thru the air. Tap water has been treated with fluoride for teeth and chlorine to kill pathogens. It may also have a high mineral content from ground confinement that isn't beneficial to the plants.

what he said

No big difference, really.
Plants will be quite happy with either.