There are now 21 water treatment works in Hong Kong with a total output capacity of 5.0 million cubic metres per day.
During the water treatment process, raw (untreated) water is dosed with chemicals under mixing for coagulation and flocculation and then passes to the clarifiers where settlement of impurities in water will take place. Clarified water then flows into filters of sand and anthracite for removal of the more finely divided particles.
The filtered water passes into contact tanks where chlorine and hydrated lime are added respectively to disinfect and control the pH of the treated water. Fluoride is also added for dental protection. A small amount of residual chlorine is maintained in the water to prevent bacterial growth on the rest of its journey. The treated water is pumped into a system of watermains, stored in service reservoirs and then supplied to the public.
has been treated by the water treatment works of the Water Supplies Department of Hong Kong Special Administrative Region