i just sat up a diy co2 system today. instead of a 2 liter, i used a gallon jug. yes, it will hold the pressure. it's thicker than a 2 liter bottle. my question is though.. since a gallon is almost 2 liters more than a 2 liter, do you think it will hurt? my recipe was 2 cups sugar, 1/4 tsp yeast, warm water. i filled it up 3-4" below the top. thanks in advance.