I live just off 17th ave in a building built in the 70's.
The water on the left is RO, the water on the right is straight out of the tap.
I can't get a decent output from my RO. DI is useless after about 10 gallons, and my RO can usually only take it down to about 35-40 ppm.
I'm sure I'm one of those cases where I have worse water than the rest of Calgary (my old place was about 180 out of the tap), but I don't even use my tap water to cook with, let alone advocate it for a reef tank.