The clean water in the US has also been purposely contaminated with Fluoride (itself toxic) in the form of industrial waste products such as Hydrofluoro-Silicic Acid.
You can see a video on YouTube of this chemical added to your water burning through concrete when spilled.
When the OP said there must be something in the water, he was right.
I don't know if they're doing the same thing in China, but probably not. Although I have heard of unsafe levels of fluoride in rural areas in China, it wasn't purposely added.
If you want to get down to brass tacks, I find I am far less docile here. For all the shit taking place stateside these days, they probably do need to ensure that people stay docile.