A tank assembly (70) for storing a liquid reductant (74) includes a tank (78) defining a chamber (82), a filler tube (94) having an opening (102) and at least partially defining a fill passageway (98) from the opening (102) to the chamber (82), and a vent system (130). The vent system (130) includes a recirculation line (150) that provides fluid communication between the chamber (82) and the fill passageway (98). A float valve (174) in the recirculation line (150) prevents the conveyance of liquid (74) through the recirculation line (150).