This epitomizes the flawed nature of our political system. I really think that we have far too many elected officials and not enough commissioned ones (EDIT: I should have said appointed) who can be fired or otherwise held accountable. As I age I'm more and more inclined towards technocratic government.
Indeed, a quick search for 'ghost reservoir' turns up stories from places as diverse as New Jersey and Singapore, although these are related to drownings, which would present a much more significant health hazard. Fortunately, authorities in those places seem to have kept things in perspective. It's a lot better to just go on TV, tell everyone that the water is actually fine, thank you, and then drink a glass of it on camera to underline the point. Sure, a few crazies will think there's a big cover up and post about it on infowars or wherever, but those are the same people that think flouridation is part of a government plot to kill us all. Fuck them.
If it is, then it's ill-placed. A commissioner is someone who is granted a commission and is appointed.
http://www.oregonlive.com/portland/index.ssf/2014/01/portlan...
With a well educated populace, a stupid "better safe than sorry" act like this would result in losing the election, not saving it.
Now, I don't know if it's actually possible to achieve that state. But I think that any other fix is just going to work around symptoms rather than addressing the root cause of the problem. Political pressure still applies to appointed posts, after all, it's just somewhat less direct. Instead of the water commissioner making this call for his own election, he'd just be told to do it by whatever elected official is above him.