Book excerpt: The aim of the book is to provide domain-specific text/reference material pertaining water chemistry/hydrogeochemistry catering to students of geology, hydrogeology, civil engineers, hydrochemistry and environmental sciences. It will also be very much useful to professionals involved in water supply, treatment, and researchers engaged in water chemistry. The book is intended to provide ample realistic examples on water quality pertaining to varied geological environs, which would help in easy understanding of concepts. Question bank and exercises with keys/answers are provided for each chapter, which would facilitate the readers to assess their understanding and also facilitate in competitive tests. The book covers all the topics related to water chemistry with emphasis on ground water. Interpretation techniques for major ion content of water are deliberated exhaustively. Procedure of preparation of plots, graphs and calculations of various indices both manually and using simple software are discussed in detail.