Actually leakage is caused by differences in pressure. Ideally the vacuum at the top is equal to the available air at the bottom (or less). Applying more vacuum can only pull more liquid into the carto's center tube.
Also, to avoid leakage when not in use ... lay it on it's side. Gravity really is a law of physics.
Also, to avoid leakage when not in use ... lay it on it's side. Gravity really is a law of physics.