Diesel exhaust fluid tank breather assembly

A diesel exhaust fluid (DEF) delivery system includes a tank (12) for DEF, usually a urea aqueous solution, and a pump receiving the DEF from the tank (12) for pressurization and delivery through a nozzle to the exhaust system of a work machine. A breather assembly (14, 70) is provided for the DEF tank (12) and includes a housing (46, 48, 72, 76) having an inlet (60) for ambient air and a particle filter (54, 80) adjacent the inlet (60) for filtering particles. A hydrophobic membrane (62, 84) is interposed between the particle filter (54, 80) and an outlet (50) leading to the tank (12) for preventing outflow of DEF vapor and condensate.