Firstly, if this is an opinionated essay or paper, it is fine to state "I like water, and so should everyone else". However, if it not... I would avoid this. Also, since it is an introductory paragraph, I would not use rhetorical questions. From what I understand, you are trying to convince people in this paper why water is important... I would remove the "they should!" statement because it is informal and very assertive to a reader.
Also, you do not want to state examples in your introduction. Your introduction should be short with emphasis placed on your topic.
Hope that helped!