Of course it doesn't make sense, it's a conspiracy theory. It's an example of correlation does not equal causation, which many Right Wing conspiracy theories fall prey to such illogical conclusions.
You're doing it wrong as water is not a deadly toxin. What you're supposed to say is "people overdosed on this substance leading to their deaths." This way, it doesn't overtly label it as a toxin, but leaves the reader to think it is.