I usually drink bottled distilled water, but there is no guaranty that there is no other chemicals in it.
However, it cannot contain metals.
If I remember correctly, if the water says spring water, it has to be from a spring and not filtered unless it says so.
If u get a distiller, make sure it has a glass water collection jar because plastics are pourus and fungus will eventually develop and I was totally unable to get rid of the fungus even using bleach.
Here is a great site with water treatment comparisons