Worst water I've ever seen was in the San Francisco bay area. Scale build up 2-3 inches thick often in machines I overhauled. never seen anything close to that bad here in Portland OR or out of Salem.
However there is city water and well water. City water is pretty good, well water not so much. Even Portland sometimes switches to well water during times of drought.
A three way filter, sediment, taste (carbon) and limescale inhibitor (phosphate) are common and good insurance. Don't forget to change them when due. In bad water areas, a high quality resin filter is both recyclable and durable.
The Original "It's A Grind", Portland Oregon - Espresso and Coffee Equipment Specialist since 1992