Our club recently ran a test of people's waters. We're in central California, and had ranges from 80-350 for the most part, with one farming community having a couple members with over 600!
Phoenix and the surrounding cities have very hard water and high TDS due to the sources, the Colorado River(which is 200 miles away and delivered by an open canal which causes massive evaporation and concentration of solids) and the Salt River ( three guess as to how it got its name and the first two don't count!). Treatment plants do not treat for TDS and hardness as it is considered astetics since it is not detrimental to human health.