Keeping an eye on how much water your air plant's tank uses and cleaning off any debris can help you ensure that your plant is always getting enough water. There is no set time for changing the water in your air plant's tank; as long as it receives adequate water, it will be fine. A humidifier can also help your air plant thrive by increasing the humidity levels in your home. If you notice any wilting or browning of the leaves, you should begin changing the water more frequently.