The membrane in an RO (Reverse Osmosis) water purifier plays a crucial role in filtering out impurities, contaminants, and harmful substances from water. It acts as a semi-permeable barrier, allowing only water molecules to pass through while blocking larger particles, salts, bacteria, viruses, and chemicals. As water is forced through the membrane under pressure, it undergoes a filtration process that significantly improves its purity. The membrane ensures that only clean, safe drinking water remains, making it an essential component in the RO system for effective water purification and ensuring high water quality.