Oz is an English measure of liquid volume, amounting to nearly 30 milliliters. Therefore 1 oz of water equals 30 ml of water (29.574 ml. exactly). One liter has 1000 milliliters, or 33.33 ounces.
ounces of water: something without value, which slips between the fingers. The ounce is a measure of weight, which oscillates between the 28 Gr. of Castilian Oz, and the 33 approximately in Aragon.