The water here is pretty awful for brewing. Bicarbonate is super high, it's very high in sodium, but worst of all, the ion levels vary a ton based on the water source. You could be brewing with 50ppm calcium or 350ppm calcium depending on the time of year, and where they are pulling the water from. Depending on the municipality, there is a boat load of chlorine or chloramines in the water too.
My beers were markedly better when I switched to RO and started building my water. The same might not apply to people across the country, but here in Phoenix, it's an issue. Just taste the tap water here; you'll notice what I'm talking about.