Hydrogeology is a branch of geology that studies water, both underground and on the surface of the Earth. The goal of this book is to help you understand hydrogeologic systems on a practical level. If you end up working in a field related to hydrogeology, there is a good chance that you will be asked to predict the outcome of a water-related scenario. Will contaminated groundwater reach my water supply? Does the pumping from a well at my neighbor’s house have the potential to affect my water availability? Where are the dissolved compounds in my drinking water coming from? At what rate can the city pump water to minimize impacts on local surface waters? These are all important questions that require specialized knowledge. Through this book, we want to introduce you to the field of study (hydrogeology) that can help to answer these questions.