Hong Kong’s colonial population was around 12,000¹. Prior to its founding as a city, the population was mainly engaged in agriculture and fishing and relied on mountain streams and wells for water. Historians have noted that during the 19^th century, European merchants travelling to and from Guangzhou via the Pearl River estuary would obtain potable water at Waterfall Bay in Pok Fu Lam. In the 1860s, to meet the water needs of an expanding population, the government diverted the headwaters of Waterfall Bay to Pok Fu Lam Reservoir, Hong Kong’s first built reservoir. Today, there are 27 reservoirs still in public use, with one converted for recreational use and nine serving as irrigation reservoirs. The remaining 17 reservoirs are connected to the city-wide water supply system. In addition to collecting rainwater, the city’s reservoirs have been receiving Dongjiang water from the mainland since the 1960s. The reservoirs are interconnected and linked to a water supply network that covers 99.9% of the population, making it the lifeblood of the city - although invisible on the surface.

This chapter is an introduction to Hong Kong’s water supply system and begins by describing the development of water sources, construction of reservoirs and the operation of the various parts of the water harvesting network at different stages of the city’s development. This chapter also outlines how the Water Supplies Department (WSD) plans for the city’s future water resources in response to recent socio-economic developments and emerging issues, such as climate change. It includes an introduction to reverse osmosis technology for desalination and the development of reclaimed water and treated grey water. These measures are capable of exploiting new water resources while also containing the demand for water to strengthen the resilience of Hong Kong’s water supply.

The WSD’s century-old waterworks facilities and the rich vegetation in the catchment areas have become heritage and cultural attractions for local residents and visitors from around the world. These facilities have been regularly maintained and updated, particularly in the areas of water quality control and environmental protection. This infrastructure serves the practical needs of the public while providing them with peace of mind about safe water sources in an “urban oasis”. This chapter also presents anecdotes from Hong Kong’s water supply history, providing insight into how generations of waterworks professionals have safeguarded the city’s lifeblood and delivered outstanding service to the public.