A filter cartridge has a shell defining an upper portion with an upper interior volume and a lower portion with a lower interior volume. The cartridge is for use in gravity-fed water treatment systems having an upper untreated supply and a lower filtered container. A hydrophilic porous particulate carbon powder block filter in a polymeric binder is disposed in the cartridge. The filter has a central opening and is open on both ends. The top end of the block is fitted with an air vent tube. The lower end of the block is fitted into a rubber gasket to direct water flow into the lower container. As water flows through the filter cartridge, air is vented through the block filter central opening and out through the vent tube.