A liquid treatment system includes: a filter casing including a structural wall, a first screen formed though the structural wall, and a second screen formed though the structural wall; and a liquid treatment cartridge configured for placement in the filter casing between the first and second screens. The liquid treatment cartridge includes a cartridge casing having an upper end and a lower end, and an inflatable seal surrounding the cartridge casing at an intermediary position between the upper end and lower end. A method of servicing a groundwater treatment installation includes: vertically displacing a liquid treatment cartridge within a filter casing having a structural wall, a first screen formed though the structural wall, and a second screen formed though the structural wall.