When it is very cold, the horse will reduce its water consumption and be at risk of colic. Horses should not be fed excessively cold water, as it may bring on colic symptoms. Try a heated waterer, or take warm buckets out when it's cold outside. If nothing else, make sure to break the ice on a horse's water supply in freezing temperatures. In very cold weather, water heaters may be needed to prevent the water from freezing. If you are using a submergible electric water heater, be sure the heating element is turned on and that there is no stray voltage.

Water is the body’s built-in cooling system; it regulates body heat and acts as a lubricant. A horse drinks about 10 to 12 gallons of water daily depending on the work it is doing. Horses that are not drinking enough water will reduce their feed intake and reduce the energy intake. If the horse cannot drink or worse cannot get to water because it is frozen solid, the horse becomes dehydrated. Within 24 hours of water deprivation, a horse can lose about 4% of his body weight. After 48 hours, 6.8% of body weight will be lost, by which time dehydration has already begun affecting digestive efficiency. When this happens, the body cannot maintain a constant body temperature and becomes hypothermic. But the worst risk caused by lack of water is that the horse’s intestines become impacted and results in colic. In fact, the main reason the incidence of colic increases from December to March is that many horses don’t drink enough water in the winter months.