A newer method of serving wine at bars is serving it directly from the tap. This method is popular with environmentalists because when a bar serves wine from the tap, there is no need to use glass, plastic, metal, or other resources to make a bottle or a cap, which reduces waste. There are still some disadvantages with wine on tap because of issues related to the cork industry.
The main advantage of the wine tap is that the reservoir can hold a large amount of wine. Michigan State University
mentions that one bar uses a 1000 liter tank to store wine for the tap. A standard bottle of wine that holds four glasses is 750 milliliters, and even the larger bottles of wine only hold 1.5 liters, so the tank is holding the equivalent of 1333 standard bottles of wine.
One disadvantage of the wine tank is that wine can become contaminated. Fungus that grows on the cork is a significant problem with corked wine. If fungus gets into the 1000 liter tank, it can spoil all of the wine, which is very wasteful. It is much easier to discard an individual bottle of wine if fungus grows in the bottle.
Another advantage of the wine tap is that it is easier to make sure that each glass is the same size and receives the same mixing. Other types of restaurant taps can release a standard amount of a drink, and even automatically shut off to prevent overfilling a glass. The wine tap prevents overfills or underfills of each glass, and can automatically record how many glasses are served.
A disadvantage of the wine tap is that the bar no longer needs to purchase bottles that contain cork. The cork industry is important in Portugal and Spain because cork trees grow in wilderness reserve areas. If wine buyers no longer need to purchase cork, the extra income from this wilderness goes away. The local governments will not receive tax revenue from the cork trees and will have an incentive to chop them down and allow developers to build apartments and condominiums.