Hong Kong can be justifiably proud of its infrastructure. There have, however, been several unexpected hiccups. The recent cases of excessive lead content in the drinking water are a reminder that slack building maintenance is more than an aesthetic concern; it can affect public health. Like many ancient peoples, the Chinese discovered and made extensive use of groundwater for drinking. The Book of Changes (or I Ching ), originally a divination text of the Western Zhou dynasty (1046-771BC), contains an entry describing how the ancient Chinese maintained their wells and protected their sources of water. First of all, the bottoms of wells were regularly dredged to keep the water clean. The cleaning of wells even became institutionalised as a feast day in some places. Then the inner walls of the wells were reinforced with ceramic bricks and tiles, to prevent soil and other impurities from falling into the water. Lastly, the openings of the wells were covered to safeguard against contamination from above ground. Despite all these precautions, contamination of water was unavoidable, especially in densely populated cities. Knowing early on that drinking dirty water made them sick, the Chinese boiled their water, and allowed the sediment to settle, before using it for cooking and drinking. They also obtained drinking water from other sources, such as mountain streams and rivers.