A siphon guard includes a housing having an inlet and an outlet. A primary flow path is disposed within the housing and is in fluid communication with the inlet and the outlet. A secondary flow path is disposed within the housing and is in fluid communication with the inlet and the outlet. The secondary flow path has a higher resistance to fluid flow than the primary path. A valve is disposed within the primary flow path. The valve has a valve seat and a first ball and a second ball. The first ball is movable by gravity between a valve closed position, where the first ball is in contact with the valve seat, and a valve open position, where the first ball is spaced from the valve seat. The first ball is disposed between the second ball and the valve seat. The second ball is movable by gravity between a valve closed position and a valve opened position.
