Water is necessary for life because it acts as a solvent for many substances, including salts, sugars, and amino acids, which are the building blocks of life. Water also helps regulate the temperature of organisms and acts as a lubricant for joints. Additionally, water plays a crucial role in many biological processes, including cellular respiration, metabolic reactions, and transport of nutrients and waste products. Furthermore, water helps maintain turgor pressure, which allows plants to maintain their shape, and helps protect delicate tissues in animals. Overall, water is essential for the survival and proper functioning of all known forms of life.