We're on a private water supply. The acidity is just fantastic for making good beer, although the water is very soft and adding a few trace elements is handy. Because it comes from a peat bog the water is loaded with organics. I've often wondered what affect these organics have on the beer. Anyway, we've been brewing for three years now and the beer is good, so a change to the water supply would really mess things up.
The problem with the water is that the acidity corrodes copper leaving green stains down the baths. We decided to install a limestone filter bed this winter to stop the problem, but this upset the balance of the water for the brewery. A bypass route was installed with brand new 25mm blue pipe giving pure high flow water for the brewery. When used with the new cooler I bought last year it cools 2.5 brls of wort in around 30 minutes, much better than the 3 hours it used to take.
Trouble is the output is too close to the water treatment pump. The shock of the pump starting and stopping tends to blow apart fittings. 25mm pipe fed with 60psi water sure makes some dampness when unimpeded.
I brewed today. Light Cascade at 3.4%. Next week I cask it and then brew some more as part of my second brewery workshop. There are still places available if anyone is interested.