This is definitely a bit confusing, so I'll have our team update this page with better information. If you fill the jug to the line just below the handle with water and no 2 part additive dry mix you will be able to fill with 4 liters of water (1.05 gallons), but if you fill the jug full to the cap with just water you will find the jug holds close to 1.2 gallons (tested by weight). I believe the description was factoring in the use of mixing dry calcium chloride, soda ash, etc. with the mix which would reduce the volume of water needed to fill. This adds to confusion so our team will be updating the page to avoid confusion.