Some reasoning:
1 gram of water equals 1 ml of water.
Water expands to approximately 1600 times in volume of steam at 1 bar pressure.
So that gram of water can become 1.6 l of steam.
Let’s then assume a certain amount of over-pressure is required to make it pop out of the filament during printing that volume will be less but still considerable.
And 1 kg of filament usually contains much more than 1 gram of water.