i moved here in 2002, my rice cooker and the water thermal boiler (national) have all the 110-220V, TV and mini hi-fi (sony), video (china brand), computer all o.k. to bring here without using the transformer.. they don't require any switching. only for the radio-cassett (AIWA) need to shift the voltage from 220 - 110V).
among all my belongs, only the 5.1 home theatre system need the transformer..
chinese people here usually install the filter system at home and not drinking water from tape. lots of filter system here, no ruch, could come and search it yourself.