The sacredness of water
In a world in which water is incredibly scarce, what little water remains on Earth is sacred. In fact, society creates a new position called a tea master. Tea masters are responsible for cultivating water resources but can't divulge where the water reserves are (no one but the tea masters know where the waters are around their villages). The tea masters are perhaps the most important people in the society described in Memory of Water. The fact that they exist continues to show how vital water is and illuminates that water, which has become scarce, is now sacred.
Climate change
It is because of climate change and global warming created by humans that water has become a very scarce resource on the Earth in Memory of Water. Climate change is caused by an increase in greenhouse gasses, often caused by industrial activity. In the novel, climate change has caused society and the world to change significantly (for instance, China has invaded and controlled almost all of Europe). The novel provides a stark warning to its readers: start to treat the world better and stop treating it like a dumping ground. Otherwise, humans will be in a position that they don't particularly like and in a position that makes their life significantly harder.
Violence
Violence is another important theme in Memory of Water. The world, as a result of climate change and global warming caused by humans, is seemingly always feuding and/or at war. For example, China has invaded Europe and is now in control of much of the continent. Beyond that, wars constantly erupt over fights about water, which is the most scarce resource in the world in the novel. Before water became scarce, people lived in relative peace and tranquility. However, as water became more and more scarce, the characters in the novel had to contend with violence and war, both of which became a bigger part of their lives. In this theme, the novel makes an important point: when people struggle to find the tools necessary to survive and thrive, violence, unfortunately, becomes commonplace.
