The answer is 4 32 US Ounces in a gallon. 32 US ounces = 1 quart. There are 4 quarts in a gallon. 4 x 32 = 128 US ounces in a gallon.
If the water bottle is 32 ounces, then only 4 of these make up a gallon. A 1-liter bottle of water is approximately 33.8 ounces, so approximately 3.8 of these bottles make up a gallon.