Well I'm almost completely sure that the fluoride (dissolved sodium or calcium fluoride) is pretty unreactive when it comes to 4-AcO-DMT and other tryptamines / PEA's. Even alcohols like x-HO-x-T's shouldn't react with it.
The fluoride is apparently sometimes added for dental advantages.
So you should be in the clear. But because chemistry is such a complex and flaky thing personally I wouldn't even take this miniscule risk and get some pure unadulterated water. Depending where you live tap water would even be safer. Because chemical compounds can sometimes exist for 0,001% in another form and if this form is reactive it would mean you get degradation, however slow it might be it could be faster than with just pure water.
So in conclusion: should be quite fine. But just make a habit out of using pure H2O and alcohol or use vodka.
edit 1: Matterofperception, I really don't think it is easy to just deacetylate a compound with nothing but water - you would need acetyltransferase (or transacetylase) in your body to achieve that. [ok so thats false]
edit 2: Having said that, there seem to be some people who notice some general degradation in solution - if it would turn to 4-HO-DMT then it would still be active but something else just might be happening. The reports are vague, some notice diminishing effects per dose and others notice no degradation after months of liquid storage.
I would strongly advice to use a good solvent, low temperatures and even take measures against oxygen. You might do well to only dissolve a minimal amount of substance and maybe experiment with an added anti-oxidant like throwing vitamin C (ascorbic acid) in there. I know I will when I get 4-AcO-DMT. There seems to be promise for 4-HO-DMT protection and I suspect the acetyl as well.