The primary reason why an incubator needs water is to maintain humidity. Humidity is important for a number of reasons, including:
* To prevent the eggs from drying out. Eggs are composed of approximately 70% water, and they will lose moisture if the humidity is too low. This can cause the embryo to become dehydrated and die.
* To facilitate gas exchange. Oxygen and carbon dioxide must be able to move freely through the shell in order for the embryo to breathe. High humidity helps to create a moist environment that allows for easy gas exchange.
* To help regulate temperature. Water has a high specific heat capacity, which means that it takes a lot of energy to change its temperature. This helps to keep the incubator temperature stable, even if the room temperature fluctuates.
Most incubators have a water reservoir that is located at the bottom of the unit. As the water evaporates, it creates a humid environment inside the incubator. The humidity level can be controlled by adjusting the amount of water in the reservoir. Some incubators also have a fan that helps to circulate the air and distribute the humidity evenly.