Electricity in China is 220V, 50 cycles, AC. Two-pin sockets and some three-pin sockets are in use. Most of the hotels have a socket in the bathroom for both 110V and 220V. However, outside of the bathroom, only 220V sockets are provided.
The tap water in China is always not safe to drink. Mineral water can be bought everywhere. Boiled water is sometimes offered in thermos bottles in hotel rooms, but you also need to make clear whether it is fresh or not. We kindly suggest you drink the mineral water or soft drink instead of tap water.