Never drink anything except from a sealed bottle, by a major brand, that you opened yourself. Wahaha is a popular brand and we bought it all over China. They also make tasty fruit drinks which were nice when it was 110 degrees. (Don't waste your money on Evian or Perrier -- way too expensive there.)
Go to some local shops and buy large bottles of water to keep in your hotel rooms. The hotels will also give you some for free every day.
Use bottled water to brush your teeth. Make sure you don't swallow any water in the shower.
Bring your own bottled water to all meals. You can order it at the restaurants, but they will charge you a lot more.
Never eat fresh fruit, veggies, or anything raw.
No ice in anything.
No juice at breakfast, since it is made with tap water.
When you get glasses of water at a restaurant, ask the waiters to take them away. If the water is sitting there, you might drink it by mistake.
Put a towel over the sink at the hotel, to remind yourself not to drink the water.
Make sure to drink enough. It is easy to get dehydrated following these rules. (I did somewhat.) If it is a hot day, buy and drink a 1/2 liter bottle every couple hours.
Don't be daring and try to break one of these rules. It is not worth it. You can be sick in bed for 3 days, unable to care for your new baby!
Chuck Connell