How much do wild horses eat in a day?

Horse typically drink 0.5 to 1.0 gallon of water a day per 100 pounds, so a 900 pound horse would drink 4.5 to 9 gallons a day in stable weather conditions. If the weather is particularly cold they may not drink as much and if the weather is hot they will drink more.

The amount of water consumed will also vary with availability, if water is not available at all times then a horse will try to drink as much as their stomach will allow when they do find water.