Water supply and sanitation in Hong Kong
Water supply and sanitation in Hong Kong is characterized by water import, reservoirs, and treatment infrastructure. Though multiple measures were made throughout its history, providing an adequate water supply for Hong Kong has met with numerous challenges because the region has few natural lakes and rivers, inadequate groundwater sources (inaccessible in most cases due to the hard granite bedrock found in most areas in the territory), a high population density, and extreme seasonable variations in rainfall.
Source: Wikipedia — Water supply and sanitation in Hong Kong (CC BY-SA 4.0)