Water is a necessity when it comes to everything involving life on this planet. For most, water is an accessible resource that can be achieved in many ways. Two of these most popular ways happen to be between tap water and bottled water. Although both provide the same basic idea of hydration, tap water is clearly the better option for the planet.
This is my interpretation of how you could write your intro paragraph. Although I do not know your points you can talk about how plastic waste is a big problem and how in some places they put fluoride in the water, which helps everyone's teeth.
Hopefully, this helped
