My experience with WV American water is this:
Taken from the Elk river, last time I tested it it was about 80 ppm TDS-- pretty darned good. You guys are posting 300ppm. What's up with that??? That is more akin to St. Albans city water. The only potential problem With Charleston's water that I see-- assuming 80 ppm (pretty soft) is that they buffer their pH with somethingorother phosphate (I forget exactly what) and you end up with 5ppm phosphates.
Like I said, I haven't tested WV Am H2O in a while so my data is out of date. And it does not seem to matter how much nutrient I dump into my tank, it miraculously consumes it but if you have phosphate problems-- may be a bad idea. Also, water treatment plants have to alter what they put in the water according to what is in the source water at the time. After all, their goal is not to make it good for reef tanks, but to make it safe and palatable to drink. Therefore, the parameters will vary.
That is where RO units come into their own. You know what you are starting with-- pretty darned clean, pure water. That eliminates a lot of guesswork.