You can also try contacting them to find out what they put in the water.
I have a handy "what's in the water" sheet that my water company mailed to me recently.
Like others said, that doesn't protect you from surges when they put extra crap in the water to flush things out. I age my water and also use prime. I look at it this way: By aging and using prime, I make sure that the water has no chlorine/ammonia/nitrite, and the insurance really isn't that expensive. BTW along the process of aging the water I also heat up to the right temperature.