Desalination is a recurrent term in our era. In fact, it is a technology that went through a huge development since its apparition, and today it is a reliable water treatment technique that allows producing drinking water from oceans. Desalination has also benefited from technological advances in pumps, energy recovery devices, machine learning, and data science. Reverse osmosis technology is today the privileged technique for desalination used in thousands of facilities around the world. In this course, we will discuss reverse osmosis desalination from many angles:- Firstly, we will discuss the reasons we need desalination- Secondly, we will review seawater composition- Thirdly, we will explain how the process of reverse osmosis works- Next, we will explore energy consumption and the cost of reverse osmosis desalination- Finally, we will shed light on the environmental impacts of the reverse osmosis process. After the completion of this course, you will understand better reverse osmosis desalination, how it works, its energy consumption, and cost. You will also understand how important it is for many countries to deal with water scarcity and climate change. You will also understand the environmental impact problems desalination can have, and how it is important to mitigate these effects to preserve the ecosystem. I hope you enjoy the course.