“Do you know Dasani water is tap water? Now what if that tap water was unfiltered (like in NYC) and there are rabbanim (I know rabbi belsky disagreed) that say that it needs to be filtered
In that case does water need a hechsher?”
You only need a hechsher if you want to cater to a market that hold’s of the the stringent shita of that Rav.
Ask yourself a simple question: If you met the Shaagas Aryeh, or the Radvaz, etc and told them that in 2022 we have a symbol that says water is kosher, what would they say to you?