Environmental Engineering is a critical and dynamic field that addresses the interaction between human systems and the natural environment. For the Union Public Service Commission (UPSC) exams, particularly in the context of Civil Services Examination, the following topics are of paramount importance. This guide covers these topics in detail, emphasizing key concepts, significant issues, and contemporary developments. Environmental Engineering encompasses a wide range of topics crucial for sustainable development and environmental protection. This comprehensive guide provides a detailed understanding of key concepts, current issues, policies, and technologies relevant to UPSC exams. By studying these topics, candidates can develop a holistic understanding of environmental challenges and the engineering solutions necessary to address them. This detailed document can serve as a valuable resource for aspirants, ensuring they are well-prepared to tackle questions related to environmental engineering and sustainability in the UPSC exams. This textbook provides a comprehensive overview of environmental engineering, covering fundamental principles and contemporary issues.