I crossed a significant personal China boundary the other day: I started brushing my teeth with tap water.
The tap water here in China is not safe for drinking (I understand it is safe in some big int'l hotels), so I've always used bottled water for my brushing. I even rinsed my toothbrush in bottled water. On my previous short trips, I never wanted to risk getting sick over something so preventable.
However, this practice is somewhat burdensome now that we live here. Michelle (and many others) always thought I was being a bit prissy about this anyway, so I went cold turkey and started brushing, swishing, and rinsing in tap water. So far so good.
I know you were all wondering about my personal dental care habits, so now you know. You can sleep easy tonight. :)