While I rinse the toothbrush with tap and then bottled, I never put the tap water in my mouth--bottled only. That said, I suspect there are many better ways to catch something bad in Beijing than the tap water in a good hotel.

FWIW, I almost always use tap water for brushing teeth and rinsing my toothbrush, even in most Tier 3 places, and certainly wouldn't bother in a Tier 1 city. I've got a bit of an iron stomach, though, and also used the tap water in places like Bangladesh with no ill effects...

This is one of those things where you can quickly drive yourself mad if you worry about it too much: i.e. what about accidentally swallowing a bit of water in the shower? Or maybe that restaurant washed the dishes in tap water and some got left behind? I'd be more concerned about the dangers of Chinese traffic and the chronic "fog" that engulfs most cities than any bacteria in tap water.

I used to be paranoid about the need for bottled/boiled water for everything, but gradually moved to using tap water in Ningbo for washing vegetables (including for raw salads), and also for rinsing my mouth after brushing. After many months I haven't yet gotten sick from this, although food from a couple of small restaurants have given me two days in bed.

You're nuts- ni shen jing bing

I've always just assumed that the likelihood of getting sick from incidental consumption of very small quantities of non-drinkable tap water (i.e. from rinsed veggies, or brushing teeth) is very small, and I've never really worried about it. I've always thought that the body can generally handle most small-scale incursions from the bacteria in reasonably clean tap water, and that as long as you don't drink it, you should be fine.

I've been brushing my teeth in Taiwan tap water (which is supposedly unsafe to drink) for almost 30 years without any problems. And I've never hesitated to eat raw veggies and salads here. But they generally practice reasonable food prep hygiene here.

On a recent trip to India, however, I was quite concerned about the lack of basic food prep hygiene, and I avoided anything raw (except for fruit I could peel), and used bottled water to brush my teeth. But I still got very sick from the food.

Binlang xishi - well go to Taiwan to find that.

In some locations you don't have to worry about bacteria. It is the unsafe levels of chlorine that has killed all the bacteria you need to worry about.

Or you could just not worry at all and have one less thing to worry about I've never even thought of using bottled water to brush my teeth, ect. and I'm still alive and kicking, there are also 1.2 billion people who do the same thing I do and most of them are doing OK.

Timely report by People Daily on the epedemic water polution.

http://english.peopledaily.com.cn/90882/8145140.html

Maybe that was the only perk of staying in a mainland (non-chain) budget hotel- water coolers. Not to brush the teeth with, instead to prevent going out and buying a (refilled) bottle of 农夫山泉.