If someone evil has access to the water supply, is radioactive material the worst they could do? that'll, what, give some people cancer which is really bad but it'll take a while to get them. If people wanted to be shitheads, they could already dump arsenic or LSD into the water supply, or any number of others things. that are already available to them right now! Have you personally tested your taps chlorine or flouride or lead levels recently?