The book (Hidden Water Divide), meaning the science of extracting groundwater, which deals with the basics of the field of groundwater, methods of inference, and knowledge of its quality, and methods of extracting and benefiting from it. The book covers the topic in many aspects that start from the nature of the land, climate and soil, through the nature of the water and its movement in nature, ending with the necessary engineering works from the work of design, space, maintenance and contracting.