The book will develop an understanding of methods of demand and population estimation in the human and natural environment. It contains concepts about the types of demand, water requirement for different types of domestic and non domestic uses and its temporal as well as spatial variation and forecasting. It shows also methods used to select water source and to evaluate capacity and quality of the source. It deals with surface and subsurface sources identification, selection, engineering, development and related water quality considerations. The last three chapters of the book deals about various type of sewerage system. It also gives ideas how to plan the system and how to make sewer layout. It describes the different types of sanitation system (water carriage and non water carriage), septic tank design, sewerage system and planning of sewerage system projects.