Tender For corrigendum : providing of annual maintenance services for water purification and conditioning system (version 2) - potable water purification system reverse osmosis or uv based; 3 to 5; package-5 : water purifier and conditioning system maintenance involving basic servicing, ..,annual maintenance services for water purification and conditioning system (version 2) - drinking water cooler; 3 to 5; package-3 : water purifier and conditioning system maintenance involving basic servicing plus maintenance of filters and and membr..