For you information, that "zero water" filter is not that great for your health. It removes all the minerals and other bits in the water, and water without those minerals is not as good for you. Ultrapure water can absorb some of the minerals in your body, which obviously isn't a very good thing.
Also, fluoride in the water is the opposite of bad, it's good for your teeth. It's in toothpaste for a reason! There is no reasonable evidence that fluoride causes any major health problems, in fact, the fluoridation of water is dubbed as one of the largest public health accomplishments in a while. In addition, the fluoride added to water is miniscule, tiny, far far too low in concentration to be toxic. It also occurs in plenty of foods naturally too (fruits, seafood, spinach, etc.)
Some more information of fluoride:
https://my.clevelandclinic.org/health/treatments/11195-fluoride
https://www.cdc.gov/oral-health/prevention/about-fluoride.html
https://www.sciencedirect.com/science/article/abs/pii/S000291652334718X