A filter unit includes a body portion and an engagement protrusion that extends from the body portion with a first water containment seal. At least one cross-section of the engagement protrusion at a location of the first water containment seal, taken perpendicular to a central longitudinal axis of the body portion, includes an egg-shaped outer perimeter with a single axis of symmetry. At least one engagement surface traverses around at least part of the body portion. The at least one engagement surface has a linear movement section for linear movement of the body portion. The linear movement section transitions to a rotational movement section for rotational movement of the body portion. The rotational movement section is angled relative to the linear movement section. A water inlet path and a water outlet path extend through a portion of the engagement protrusion defined by the at least one cross-section.