Alberta Tap Water

[YEGReef]

Starting my first reef tank and I initially ordered a Spectrapure RODI system, it came in defective so now I have the opportunity to return it and get my money back or replace it.
The plan was to replace it and use RODI water, the tank is a 250 Gallon.

However talking to a few members in Edmonton, all of them are saying return it, get my money back and just use tap water with prime. Their tanks looks amazing, and they're growing plenty of different coral.

Is that a popular opinion in Edmonton or Alberta? Have you had success with tap water or have you seen the difference RODI makes?

Thanks!