A fluid ounce (fl oz.) is a unit of volume used for measuring liquids and is equivalent to 29.57 mL (1 US fluid ounce).
An ounce, onthe other hand, is a unit of mass equivalent to 28.35 grams.
SInce you know that water has a density of
The volume would be
You would need 32 Imperial fl. oz. or 31 US fl. oz. of water.
A fluid ounce is a unit of volume, not a unit of mass. To convert to mass, you must know the density of the liquid.
To complicate matters, there is an Imperial fluid ounce and an American fluid ounce.
In Imperial Units
1 Imperial fl. oz. = the volume of 1 avoirdupois oz. of water
So 1 fl. oz. = 1 oz. and
In American Units
1 US fl. oz. = 1.043 oz.