An Environmental Engineering to the Engineering Students of Civil Engineering and Environmental Engineering and also to the students preparing for competitive Examinations. The course content has been planned in such a way that the general requirements of all engineering students are fulfilled. During my experience of teaching this subject to undergraduate and post-graduate engineering students, I have observed that the students face difficulty in understanding clearly the basic principles, fundamental concepts. To meet this very basic requirements to the students, a large number of the questions taken from the examinations of the various Universities of India and other professional and competitive examinations. The book is written in a simple and easy to follow language, so that even an average student can grasp the subject by self study. I am thankful to my family members, colleagues, friends, students who encouraged me to write this book. Every effort was made to eliminate errors in the text book; Suggestions from the readers for the improvement in the book will be most gratefully acknowledged.