Chemistry is a branch of physical science that studies the composition, structure, properties and change of matter.
Daily water consumption varies quite a bit. Season of the year, workload, reproductive status, diet, and climate factor into the volume of water needed by a particular horse on a specific day. As a starting point, the average horse drinks between 5 and 10 gallons (19 and 38 liters) of water each day. The horse may need slightly less if it is grazing lush pasture because fresh grass contains a high percentage of liquid.
How warm the water needs to be depends on the individual. Some horses will drink water that's 32.5* Farenheit! Horses are very suspicious about any change, so if they're used to the water getting cool as the weather cools off and you warm the water up, it's going to be different.