Here are some compounds that may be in your drinking water:
Analgesic meds (ibuprofen, etc.)
Hormones from birth control pills
High blood pressure medication
Heart medication
Cholesterol medication
Anti-depressant medication
Antibiotics
ad infinitum ...
Basically, whatever meds you pee out will remain in the water because water treatment plants do not have the ability to filter out hormones and medications.
Here are a few chemicals that are added to most drinking water:
Liquified chlorine
Fluorosilicic acid
Aluminium sulphate
Calcium hydroxide
Sodium silicofluoride
The problem with RO and distilled water is that there is no trace mineral content, and that's not good. RO wastes a lot of water, too.
But I can't really answer your question. Calgary's tap water is pretty good (we're rated an A+), although we still fluorodate the water, and I don't like that. Regardless, it's still better than bottled water. And it's VERY hard because our water comes directly from the Rockies and is loaded with minerals. Tastes really good, too. But you get hard water mineral build-up in no time.