The best technology depends entirely on your water source and its Total Dissolved Solids (TDS) level. If your water is Borewell or Tanker supplied (TDS generally above 300 ppm): You definitely need a system with Reverse Osmosis (RO). RO technology is the only effective method for reducing high TDS, heavy metals, and hard salts. Look for RO purifiers with a TDS controller to retain essential minerals. If your water is Cauvery supplied (TDS generally below 200 ppm): An Ultra-Filtration (UF) or Ultra-Violet (UV) purifier might be sufficient. These remove bacteria, cysts, and viruses, but do not significantly alter the TDS level. For extra safety, especially during the monsoon, a UV+UF combination is recommended.