Now there were six water pots of stone set there after the Jews' manner of purifying, containing two or three metretes{2 to 3 metretes is about 20 to 30 U. S. Gallons, 16 to 25 imperial gallons, or 75 to 115 litres.} apiece.
firkins --  KJV, this measurment equals about 8 to 9 gallons, thus the water jars would hold about 20 t0 30 gallons. At 24 gal. per jar there would be about 144 gal. of wine produced.