Peace lily growing in water

I bought this plant probably close to 7 months ago. I used to have betta and grow these plants in this vase. This time I decided to grow the plant sans the fish. At first the plant did not take off very well, probably because I was not making sure it was always full of water. It is important that all the roots remain covered with water at all times. Since I make it a point to water this plant every other day or so it has regular started to grow. I believe the plant is supposed to do better with filtered or distilled water, but I just use regular tap water and it seems to do fine.