A drainage system for use with a slack adjuster for a railway brake rigging wherein the slack adjuster includes a main spring housing, a cone nut housing enclosing a critical operating area of the slack adjuster, and an over travel housing. The drainage system includes at least one opening extending through a sidewall portion of the main spring housing. The opening is configured to allow fluid and/or contaminates to drain therethrough to reduce exposure of the critical operating area of the slack adjuster to the fluid and/or contaminants. A seal/splash guard can be provided at the intersection of the main spring housing and the cone nut housing to prevent fluid and contaminants from entering into the cone nut housing.