I came back with two liters yesterday (just me traveling.) Signs in the duty-fre shop says two liters per person. You can't have your purchase until you are boarding your flight, except for the local liquor products which they wrap securely and you schlep them around with you in the departure area. You can take more, if you want, by declaring the quantity on your US Customs form and you would be responsible for paying duty for the excess over what is duty-free in the States.