The groundwater of Kathmandu Valley in Nepal contains very high concentration of ammonia nitrogen which is in excess of WHO guideline value for drinking water. This study mainly focuses on the removal of ammonia nitrogen in water by adsorption in locally available over burnt brick. The study was carried out in a 4.2cm internal diameter column of 120 cm length packed with over burnt brick in up flow mode. The study showed that the ammonia nitrogen removal rate increased with increase in contact time which decreased with time until steady state condition is attained .The contact time...