Which is worse on overall health- untreated tap water or aspartame?

Hi. I am curious about this. My family and I own a water ionizer but it's in need of repair. I am working toward getting it fixed, but in the meantime I have been buying bottled water for my family and myself to use, and then refilling the empty bottles with water from a water machine at my local supermarket.

I've noticed the last few times I have ordered pizza for my family and myself, my mother asks me to order diet soda. I have asked her why doesn't she want to order bottled water, since that is healthier but she says it's not enough.

I am glad she stopped ordering regular soda- all that sugar that is in it is not good for anyone. My mother and I saw a public notice on TV that stated that soft drinks are poisonous, especially if you consume them in large quantities.

Untreated tap water is bad because it's loaded with chemicals and has fluoride in it which depletes your bones of calcium.

Aspartame, according to what I read online, is one of the worst artificial sweeteners out there. It is linked to cancer.
There's a number of health risks tied to aspartame:
https://www.medicalnewstoday.com/articles/322266.php

Other bad artificial sweeteners are erythritol and sucralose.

I usually and generally avoid anything that has aspartame, erythritol and sucralose in them.

Which is worse on overall health- untreated tap water or aspartame?

Please help- thank you