How often do I need to drain the water tank? Jessica 05 October 2021 11:41 Updated We recommend draining your water tank before it reaches the line in the tank, as this may cause your AC to shut down. Related articles What size is the window kit? Why is the window kit heat exhaust hose so short? Can I buy a longer heat exhaust hose? Will my Air Conditioner unit cool my whole house? What size Air Conditioner shall I get?