River Water Quality

The potential for pollution in Hong Kong's rivers and streams is a significant threat, given the large concentrations of population around the many waterways. Here you can learn more about the state of our rivers and the Government's work in ensuring the highest environmental standard are met.

The Importance of Our Waterways

Hong Kong's steep terrain and high summer rainfall mean that there are many rivers, streams and concrete-lined channels, particularly in the New Territories. It is crucial to keep these waterways clean and free from pollution as they are beneficial in more ways than one. The upstream provides a steady supply of drinking water, a portion of which feeds our reservoirs, and the downstream reaches can be used for irrigation and help to preserve various forms of aquatic life. They also serve as a passage of storm water to the sea. A polluted waterway will not only affect your health, but also that of Hong Kong's ecosystem.

Monitoring River Water Quality

To ensure your health, the Environmental Protection Department regularly monitors water quality at 82 sampling stations in over 30 rivers and streams. The objective is to:

• Determine the health of waterways.
• Reveal long-term changes in water quality.
• Assess compliance with the statutory water quality objectives.
• Provide a basis for water pollution control strategies.

The monitoring process involves the measurement of over 40 parameters, including physico-chemical characteristics, organics, nutrients, toxic metals and bacteria. Field measurements are performed and water samples are collected for further laboratory analyses every month.

Water Quality Index and Data

The Environmental Protection Department maintains a Water Quality Index so you can gauge the state of our rivers and streams. The Index monitors the level of dissolved oxygen, 5-day biochemical oxygen demand and  ammonia nitrogen content in our waterways. Low dissolved oxygen can be harmful to most aquatic life, whereas high 5-day biochemical oxygen demand and ammonia nitrogen levels indicate the presence of organic pollution and sewage contamination. In recent years, the majority of rivers in Hong Kong have been designated as good to excellent. Recent water quality data are available for download from the Environmental Protection Department's website.

For further enquiries on the river water quality data, please contact the Department's Customer Service Centre at 2838 3111 or by email to enquiry@epd.gov.hk.

River Water Quality Annual Reports

To remain accountable to the public, the Environmental Protection Department documents the way in which it monitors and improves river water quality every year in an easy to access Annual Report. Also available is a 20-year review, which provides an in-depth account of pollution monitoring and control measures since 1986. The reports are available in public libraries, at Environmental Resource Centres in various locations or can be viewed and downloaded from the Environmental Protection Department's website.