The author's purpose is to raise awareness and convince the consumers to change from bottle water to tap water.
This article makes reference to the damage that bottled water makes to the world. Says that many people speaks about the benefits of bottled water for health, without mentioning the environmental consecuences, using this as a marketing strategy. Speaks about how tap water is procesed and adecquately cleaned for human consumption, and compares both of them, explaining that bottled water has no benefits for health over tap water and that it doesn't even taste better.