A: In short, for most people, plain water is better. But first, it’s important to understand the definition of alkaline water. Scientists use pH to describe how acidic or basic a substance is, with a range from 0 to 14. Pure water has a pH of 7, meaning it’s neutral. Fluids with a pH under 7, such as coffee and soda, are acidic. Substances with a pH over 7, such as baking soda, are basic, or alkaline.