What does the term “gravity fed” mean in terms of winemaking?

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Dear Dr. Vinny,
What does the term “gravity fed” mean in terms of winemaking?
—John, Milford, Mich.
Dear John,
”Gravity fed,” or “gravity flow,” refers to a winery operations system that uses gravity to move wine through various phases of production. The terms aren’t regulated, but typically a gravity-fed winery is built on at least two different levels or floors, perhaps on a hillside.
If the entire winery is on a single floor, every time wine is transferred between tanks, barrels, crushers or presses, it has to moved with the use of pumps or some other such mechanism. A gravity-fed process lets—you guessed it—gravity do all the work, which is of course more energy-efficient as well. Moving wine “downhill,” so to speak, is also typically a gentler process, and the more force required to move wine from one place to another, the greater the chance that the wine becomes overly tannic, over-extracted or oxidated.
There are different designs for a gravity-fed winery, but the easiest way to imagine it is to picture the grapes coming in from harvest on the top floor and then travels downward, pulled by gravity, as the wine goes from crush to fermentation to aging and bottling.
—Dr. Vinny