Water is the most vital substance in every aspect of life, and its contamination because of the activity of mankind poses a big global challenge. Addressing this issue for drinking purposes and environmental protection is the current big issue. Many research groups worldwide have been working on effective treatment technologies based on nanomaterials during the last two decades. Water and wastewater treatment by nanomaterial-based technologies has become an aid in finding possible solutions for contaminated wastewater released from various water sources. Nanoscale materials can be seen to take on unique and unpredictable properties that make them more robust, flexible, lighter, and faster, and the particular material used for the development of devices and systems. Features: • This book presents the use of different advanced nanomaterials to treat water and wastewater. • The uses of carbon-based nanomaterials, metal-organic frameworks (MOFs), and biopolymer-supported nanomaterials for water treatment are explored, focusing on new- generation materials. • Water purification methods such as the disinfection of water using green synthesized nanomaterials, adsorption through nanomaterial-based adsorbents, and nanofiltration techniques are discussed. We emphasize efficient water treatment methods and the use of new emerging nanomaterials in the toxicological study of nanomaterials. Nanomaterials provide high-performance and cost-effective treatment for water treatment. Various nanomaterials and electrochemical methods are used to stop, remove, or neutralize water harmful organic and inorganic contaminants in water through adsorption, filtration, and disinfection.