"If you're worried about the chlorine and fluoride in tap water... Just fill a pitcher and let it sit for 24 hrs. All of that will evaporate."

Pretty sure it's bad to leave it out...not only will the Cl and F not evaporate (think of salt water, only the water evaporates leaving the salt behind - even if it was dissolved) plus mold spores/dust could get in the sitting water.

I used distilled water (you can get a gallon of it for like $0.50 at walmart) just in case cuz I have really hard water too. I was just too worried about what all the chemicals could do. I mean, too much chlorine could be bad for humans even...