If they actually treated the water properly and kept the dosage below 1 ppm it would be ok, trouble is that a lot of water treatment grids have never been upgraded since they were built.

So as more suburbs and towns are added to a grid rather than building mini-dosing stations to keep the water at the level that they need they just increase the quantity at the plant. The result is places closer to the plant get many times the max safe level of 1.5 ppm and can get more than 20 ppm so those further from the plant can get the 0.7 ppm recommended.