Water is the most important nutrient that we provide for horses on a year around basis. Horses need 2 to 3 times more water than other feedstuffs. An 1100 lb horse on a dry forage diet at an average temperature of 68 degrees Fahrenheit will need a minimum of 6-7 gallons of water per day or 48-56 lbs of water, and many horses will drink more water than the minimum. We all appreciate that the water requirement may double at high temperatures, but may not realize that at -4 degrees Fahrenheit; the quantity required is about 10-12 gallons per day, or actually higher than at moderate temperature. The onset of cold weather can actually increase the requirement for water because there is no fresh grass and the air is very dry.
There is a misconception that domestic horses can easily eat enough snow to survive. While horses in the wild do adapt to lower water intakes, partially because food intake is also frequently reduced, horses can survive longer without food than they can without water. Reduced water intake can also impair digestion and potentially contribute to the incidence of impaction colic.
It also requires a great deal of energy to eat snow, melt the snow in the body and raise the fluid temperature to normal body temperature of 99.5- 100.5. Increasing the temperature of 10 gallons of water from 32 degrees to 100 degrees takes about 1372 Calories or about the amount of digestible energy in a pound of feed. Melting the snow to get to water will take a great deal more energy and the horses will not readily eat a pile of snow the size of 20 five gallon buckets. It takes about 10 inches of snow to have one inch of water.
Providing horses with fresh clean water at an appropriate temperature all year around is a great management tool to reduce the risk of colic, maintain healthy digestion, maintain body condition and even save a bit of money on feed cost!