They raise it to 8.2 here in Portland. Here's the reason why:
"At the end of the disinfection process, sodium hydroxide (NaOH) is added to the water to raise the pH of the water to approximately 8.2 pH units. The addition of NaOH helps reduce corrosion of system piping and household plumbing, which in turn reduces the amount of lead, copper and other metals that can leach into the water from pipes, solder joints and plumbing fixtures."
I used to get grief from people that said sodium hydroxide "Lye" was bad to use as pH Up. If they use it in municipal water that people drink it won't harm the plants.