A device useful as a pest barrier system for plumbing of mobile vehicles or plant barrier system is disclosed. The pest barrier system for plumbing of mobile vehicles comprising a pest protection system having a first half, a second half, a lower portions and an upper portions. The lower portions of the pest protection system comprise a lower rim. The upper portions of the pest protection system comprises an upper rim. The lower rim comprises a lower external diameter and a lower internal diameter. The upper rim comprises an upper external diameter. The pest protection system fits within a plumbing compartment of a mobile vehicle at a gap comprising an internal diameter which is smaller than the upper external diameter of the upper rim of the pest protection system. The lower portions of the pest protection system receives a portion of a fluid drainage hose having an external hose diameter.
