EDI (Electro-Deionisation)

Electro-Deionisation (EDI) is a final water-polishing technology that combines ion-exchange membranes, ion-exchange resin, and a DC electric field to produce ultra-pure water, typical output: < 5 µS/cm conductivity (vs RO permeate at 30–80 µS/cm). EDI is **not standard** for packaged drinking water (BIS limit is 50–250 ppm TDS, RO permeate already exceeds this). EDI is typically required for: - Ultra-low TDS specialty water brands - Pharmaceutical / injection water plants - Semiconductor industries - Food applications requiring sub-1 ppm TDS For packaged water plants, EDI adds capex (₹6–14 Lakhs) and operating cost (electricity + resin replacement), adopt only if your product positioning specifically needs ultra-low TDS.