i water every 3 days- Im using about a gallon of water to five small plant holders and alot of that drains down the sink.
But RKM is right- it depends on the specific environment of your plants.. every situation is different. (Varying Humidity, Light, Wind, In/Outdoor, amount of water you use)
everyday is probably too much.
Read more and post your specifics along with pictures for the best answer.