We know Assam's water. Not water in general. Assam's water.
Guwahati's groundwater is often iron-heavy. Nagaon can have fluoride concerns. Tinsukia and Dibrugarh can carry arsenic risk. Cachar's Barak Valley can show hard water problems that are different from many Brahmaputra basin areas.
A company from outside Assam can sell you a purifier. But your water changes by district, depth, source, and season. Local knowledge is what turns a decent system into the right system for your home or business.