Abstract: A rust and scale arrester intended for use in heat transfer systems particularly for water cooling systems of internal combustion engines is mounted in place of an ordinary connection hose. Primary and secondary filter deflector screens are mounted at about 60.degree. to the flow of water from the inlet to the outlet. The primary filter deflector screen extends downward into the collection chamber and extends rearward to cause solid particles to flow outward along walls of the collection chamber. The downward extension has a forward and downward extending portion which encourages solid particles flowing downward from the first deflection screen to flow along walls of the collection chamber. The forward portion of the downward extension has openings which allow upward water flow, and the downward and rearward extending portion has openings which allow water to flow over the downward and forward extending portion to remove particles and promote water flow.