If your air conditioner is leaking water, it’s usually due to a problem with drainage or airflow. One of the most common causes is a clogged condensate drain line, which prevents moisture collected by the system from properly draining away and can cause it to back up and overflow. Another possibility is a dirty air filter, which can restrict airflow over the evaporator coil and lead to ice forming and then melting into excess water. In some cases, the condensate pan may be cracked or rusted, or the unit may not be level, causing water to spill instead of draining correctly. Low refrigerant levels can also cause the coil to freeze and later leak when it thaws. Because several issues can cause leaks, it’s usually best to have an HVAC professional inspect the system to prevent water damage and restore proper operation.