I am residing near Kapra lake near Sainikpuri, Hyderabad. The bore water of our colony is taste's ok,  but leaves white residue in water heaters. The TDS tested by a pen like instrument by a water purifier sales man showed about 400. Can adding a little alum and precipitating the dissolved salts help me in using the water for drinking or getting an RO system is the only method?

Ram Mohan
vrm_vaddadi@yahoo.com