Water quality was one of our top concerns when we moved to Shanghai. After looking at a number of options we settled on the reverse osmosis system installed by David Wang and his staff. We have been very happy with the quality of this product – we use the filtered water for washing fruits and vegetable, cooking, and drinking. (We also have the shower filters, which really cut down on the chlorine and other chemicals that can irritate the skin and dull the hair here.) David has provided top-notch customer service all along the way. We have recommended his products and his service to many others.