During travel to various part of India in general, and universities, institutions, and other educational centers in particular, where environmental engineering is being taught, it was found that little emphases is given to problem solving in wastewater was felt for a book which can help background in mathematics to solve day to day problems in wastewater engineering. Keeping this aspect in view, the authors have tried to solve varied types of problem (more than one thousand), currently being faced by student, teachers and practicing engineers alike. The Present book is not a substitute for a regular textbook on wastewater engineering. The book must be read and used as a supplementary text to assist in solving problems in wastewater engineering Emphasis has been given to problem solving based ion some on some specific fundamental principles as delineated in Standard Text Books. All type of Units (FPS, MKS, cgs, SI) have been used in order to familiarize the students with these units, currently in vogue in various text books. Also various types of Symbols have been used in mathematical expressions, and definitions of the symbols have been clearly defined in each problem. The authors are sure that the book will be well received by all concerned students, practicing engineers, and scientists.