Generally, you can never vacuum liquids 100% airtight with commercial devices, because the pressure is stronger than the liquid. Caution is advised when vacuuming liquids, I have experienced many a mess in my professional life. I use this appliance very often privately, for liquids I do it as follows: Fill, insert the bag, remove the air by hand (this works very well with a lying bag!) and then seal the bag with the welding function without vacuuming. If you want to vacuum 100% airtight, then chill the liquid deeply in a flat container and then vacuum completely or in broken pieces. Greetings LH