Abstract: A gravity-fed carbon block water filter in one embodiment includes a filter block comprising multiple sub-blocks each comprising filter media walls surrounding and defining a cavity for receiving fluid. Each of the sub-blocks is connected to at least one other of the sub-blocks by filter media of which the filter block is made. In one approach, the filter media includes about 20-90 wt % activated carbon, and about 5-50 wt % binder. In another approach, a lead concentration in a final liter of effluent water filtered by the filter is less than about 10 ?g/liter after about 151 liters (40 gallons) of source water filtration, the source water having a pH of 8.5 and containing 135-165 ppb total lead with 30-60 ppb being colloidal lead greater than 0.1 ?m in diameter. A gravity-fed water filter in other embodiments has no specified shape but achieves a FRAP factor of about 350 or less.

Abstract: A gravity-fed carbon block water filter in one embodiment includes a filter block comprising multiple sub-blocks each comprising filter media walls surrounding and defining a cavity for receiving fluid. Each of the sub-blocks is connected to at least one other of the sub-blocks by filter media of which the filter block is made. In one approach, the filter media includes about 20-90 wt % activated carbon, and about 5-50 wt % binder. In another approach, a lead concentration in a final liter of effluent water filtered by the filter is less than about 10 ?g/liter after about 151 liters (40 gallons) of source water filtration, the source water having a pH of 8.5 and containing 135-165 ppb total lead with 30-60 ppb being colloidal lead greater than 0.1 ?m in diameter. A gravity-fed water filter in other embodiments has no specified shape but achieves a FRAP factor of about 350 or less.

Abstract: A gravity fed carbon block water filter includes activated carbon particles; a binder material interspersed with the activated carbon particles; and a lead scavenger coupled to at least one of the activated carbon particles and binder material, the lead scavenger being for removing lead from water, where a lead concentration in a final liter of effluent water filtered by the filter is less than about 10 ?g/liter after about 151 liters (40 gallons) of source water filtration, the source water having a pH of 8.5 and containing 135-165 parts per billion total lead with 30-60 parts per billion thereof being colloidal lead greater than 0.1 ?m in diameter, and where the water has an average flow rate of at least 0.1 liter per minute through the filter with a head pressure of between approximately 0.1 and 1.0 psi.

Abstract: A filtering device for a gravity-flow liquid treatment system includes a first filter component that can be either exposed or adjacent to a substantially transparent region in at least a portion of a filter housing. The first filter component is capable of providing a visual indication of exposure to at least one contaminant. The contaminants for which the first filter component can indicate exposure include particles, inorganic, and organic contamination. Particle contamination is indicated by a change in color of the first filter component through particle collection. Inorganic and organic contaminants are indicated by reaction with at least one agent capable of undergoing a color-change reaction in response to at least one contaminant.