Water used for formula question

I have a question what are you ladies using for water for your formula? I have heard some people boil water or by the water or use water bottles. I have been buying the baby filtered water from Walmart but recently used CVS baby water when we were in a pinch. This water says it contains fluoride for flavor and didn’t have any other options in store so we just ended up with this one. Ever since I started using this leader I have noticed it smells different when the bottle is done and he has been more fussy. Does anyone else use the water with fluoride and have noticed a difference? Or do you think it might just be because he is turning eight weeks old? Let me know down below