Is using distilled water for a fish tank safe?

I am changing around 10% of my water every three to four days, or when it starts to look cloudy. I just removed some and wondered if i boiled it, could i put it back in my plastic jug for refill later? I don't feel safe using the tap here, even with water conditioner. I have 5 or so gallons of spring water, but that will start to add up if i keep having to buy that every month. So, would this be ok to use?