Terracotta Clay Water Filter — Traditional Water Purification

Terracotta clay water filters are one of India's oldest and most sustainable water purification technologies — documented in Sanskrit texts and used for millennia across South Asia. Red clay fired at low temperature (800–900°C) has natural microporosity of 0.2–0.5 microns — effectively removing bacteria and suspended particles. Traditional design: a porous unglazed clay pot placed inside a sealed container; water seeps through the clay wall, drips purified into the storage vessel below. The clay's natural minerals (colloidal silver in some formulations, iron oxides) provide antimicrobial action. Contemporary NGO applications: Ceramic Water Filters (CWFs) produced in Tamil Nadu, Rajasthan, and Maharashtra cooperatives are distributed in tribal areas without piped water. A CWF treating 10–15 litres/hour costs ₹800–1,200, lasts 2 years. Studies show 90–99% reduction in E.coli, Vibrio cholerae, and Salmonella. UNICEF and WHO recommend terracotta water filters as Point-of-Use technology for rural India.