Reverse osmosis (RO) is a process for purifying water by pushing it under pressure through a semipermeable membrane. This membrane allows water molecules to pass through while blocking larger molecules and impurities, such as salts, minerals, bacteria, and viruses. The process starts with applying pressure to the water on one side of the RO membrane, which forces pure water to move through the membrane to the lower pressure side, leaving contaminants behind. These contaminants are then flushed away in a waste stream, separating them from the clean water. The result is purified water on the permeate side of the membrane, which can then be used for drinking, cooking, and other purposes. Reverse osmosis is effective in removing a wide range of contaminants, making it a key technology for producing high-quality drinking water, treating wastewater, and desalinating seawater.