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.
Horses will generally consume more water than they need if given access to a palatable water source. Horses at rest in a moderate climate will generally consume between three and seven litres of water per 100kg of bodyweight. This translates to around 4-9 US gallons for an 1100 lb. (500 kg) horse. Diet plays a major role in determining voluntary water intake and requirements.