You don't have to water the Tillandsia. The plants get their water mainly from the air. Through the small hairs on the leaves of the plant, it absorbs the humidity. Because the air inside the house, can sometimes be 'dry', for example due to a heater, it is certainly good to spray the air plants occasionally with water or Tillandsia Spray. The spray contains extra minerals, which give them an extra boost and keep the air plants in top condition.
In the hot summer months, the plants do need water or spray once or twice a week This will prevent the plants from drying out.