The Winetech de-alc unit is a counterflow crossflow filter with a hydrophobic membrane. As the wine is recirculated through the filter, a portion of the ethanol follows the concentration gradient (osmosis) from the wine through the hydrophobic membrane and into the counterflow water. Since the membrane is hydrophobic, the water portion of the wine stays on the wine side of the filter; and since all the other chemical components of the wine are bigger in size than the ethanol, the membrane only lets the alcohol through into the counterflow water.