**Abstract**

Water is an essential nutrient in animal nutrition, makes about 70 to 80% of lean body mass and plays important roles in poultry metabolism and thermal homeostasis. Water provided as drinking water constitutes the largest proportion of water available to poultry followed by metabolic water and that available in feed. The intake of water by birds varies depending on the age, environmental temperature, relative humidity, certain diet constituents, type of drinkers used and rate of growth. An increase in environmental temperature tends to cause an increase in water intake while decrease in environmental temperature causes decrease in water intake. Hence, in addition to its nutritional role, water is more important for thermoregulation in chickens especially under hot conditions.

**Keywords:** water, poultry, homeostasis, temperature, thermoregulation
