A filter cage for use in a filter unit for filtering microparticles from a feed liquid containing microparticles, wherein the filter cage extends along an axis and is configured to be rotatable within the filter unit about the axis and removable from the filter unit ; the filter cage comprising: at least one filter cage sidewall extending parallel to the axis, the at least one filter cage sidewall comprising a first end and an opposing second end , the filter cage sidewall together with the first and second end defining an interior and exterior of the filter cage, wherein the filter cage sidewall is or comprises one or more than one filter media for filtering microparticles from a feed liquid, the filter media defining a filtration surface on the interior of the filter cage where filtered microparticles accumulate during filtering; a moveable member in the interior the filter cage comprising a filtration surface cleaning portion which is proximal to the filtration surface; a user operable portion adapted to be operated by hand on the exterior of the filter cage ; wherein the first end of the filter cage is or comprises an opening for extraction of filtered microparticles from the filter cage when the filter cage is removed from the filter unit and for supply of feed liquid into the filter cage when the filter cage is inside the filter unit ; and wherein the moveable member is connected to the user operable portion so that movement of the user operable portion causes movement of the filtration surface cleaning portion relative to the filter cage to detach filtered microparticles from the filtration surface to pass out of the opening at the first end of the filter cage . the filter cage comprising: at least one filter cage sidewall extending parallel to the axis, the at least one filter cage sidewall comprising a first end and an opposing second end , the filter cage sidewall together with the first and second end defining an interior and exterior of the filter cage, wherein the filter cage sidewall is or comprises one or more than one filter media for filtering microparticles from a feed liquid, the filter media defining a filtration surface on the interior of the filter cage where filtered microparticles accumulate during filtering; a moveable member in the interior the filter cage comprising a filtration surface cleaning portion which is proximal to the filtration surface; a user operable portion adapted to be operated by hand on the exterior of the filter cage ; at least one filter cage sidewall extending parallel to the axis, the at least one filter cage sidewall comprising a first end and an opposing second end , the filter cage sidewall together with the first and second end defining an interior and exterior of the filter cage, wherein the filter cage sidewall is or comprises one or more than one filter media for filtering microparticles from a feed liquid, the filter media defining a filtration surface on the interior of the filter cage where filtered microparticles accumulate during filtering; a moveable member in the interior the filter cage comprising a filtration surface cleaning portion which is proximal to the filtration surface; a user operable portion adapted to be operated by hand on the exterior of the filter cage ; wherein the first end of the filter cage is or comprises an opening for extraction of filtered microparticles from the filter cage when the filter cage is removed from the filter unit and for supply of feed liquid into the filter cage when the filter cage is inside the filter unit ; and wherein the moveable member is connected to the user operable portion so that movement of the user operable portion causes movement of the filtration surface cleaning portion relative to the filter cage to detach filtered microparticles from the filtration surface to pass out of the opening at the first end of the filter cage . <EOS>