If you have a lot of chlorine in your water, you can let a glass of water set out overnight and that will give the chlorine time to dissipate a bit.
You only need a sourdough starter, flour, water, and salt. That being said, I have had the best luck using unbleached flour and, if you can, organic flour. The natural yeast in the starter seem to do better with these flours. And as far water goes, I use tap water. If your water is highly treated you might want to consider using bottled or filtered water. If you have a lot of chlorine in your water, you can let a glass of water set out overnight and that will give the chlorine time to dissipate a bit. Those are small things and you don’t have to worry about it, but if your dough isn’t rising as well as you’d like, you might want to see if changing up your flour or water matters.