Water is a necessary nutrient, although it receives limited discussion. The water should be clean and fresh. An average size horse not in production will drink 10-12 gallons of water per day. In hot, humid weather, this amount could easily double. In fact, nursing mares often drink 20-25 gallons of water daily. It is just as important for horses to have adequate water intake in the winter. Horses can withstand severe winter weather conditions if they have adequate forage and plenty of water to metabolize that forage. Horses will not get enough water from snow or a frozen pond.