The quality of drinking-water is a universal public health concern. Water is essential for life, but it can and does transmit diseases across countries in all continents – from the poorest to the wealthiest. It needs to be emphasized that access to safe water is a fundamental human need and is, therefore, a basic human right.
Potential Health Effects
Water is a common vehicle for the spread of pathogens, including bacteria, viruses and parasites, and other environmental health hazards. The most common diseases of this type are diarrhoeal diseases. Some of the more well-known examples of water-borne pathogens include Salmonella, Shigella, Campylobacter, Rotavirus, Enteroviruses and Giardia. The majority of illnesses caused by these pathogens are only moderately serious and frequently take the form of gastroenteritis with diarrhoea, abdominal pain or vomiting of short durations. They may affect several people or an entire community, depending on the quantity or type of pathogens present in the water. Infection may occur as a result of drinking the contaminated water directly or using it for washing or preparation of meals and drinks. Some chemical substances present in water as a result of natural processes are essential in maintaining good health, but some may be detrimental to health when they occur above certain concentrations. Fluoride, for example, is an important component in bone and tooth structure. Too low a level of fluoride increases the incidence of dental caries, but an elevated level of fluoride causes mottling of the teeth as well as skeletal fluorosis.
Source of drinking-water supply in Hong Kong
At present, Hong Kong derives about 70- 80% of its raw water supply from Dongjiang (East River) in the Guangdong Province and the rest from rainfall collected from local water gathering grounds.
What has the Government done to ensure drinking water is of good quality?
To ensure the quality of the drinking-water supply, all raw water regardless of its source undergoes a series of rigorous treatment processes at the Water Supplies Department's (WSD) water treatment works before distribution to consumers. The WSD has a comprehensive programme to monitor the quality of water. Representative samples are taken from different parts of the water supply and distribution systems for physical, chemical, bacteriological, biological and radiological analyses. The quality of treated water conforms chemically, bacteriologically and radiologically to the Guidelines for Drinking-water Quality recommended by the World Health Organization. To enhance dental health in the population of Hong Kong, a carefully controlled dose of fluoride is added to the treated water.
Starting late 2017, WSD has implemented an Enhanced Water Quality Monitoring Programme, which collects random water samples from consumers’ taps for testing six metals, namely, antimony, cadmium, chromium, copper, lead and nickel. These metals could be present in internal plumbing systems, but their levels in drinking water and the corresponding health risks are usually very low if the internal plumbing systems are properly installed and maintained. Further information about these six metals in drinking water, their key health effects and health advice are available in the webpage of “Health-related Information on Metals in Drinking Water”.
To help in ensuring a sustainable and good quality supply of drinking-water, the general public is advised to:
- conserve water (tips)
- cleanse the fresh water storage tanks in their buildings at least every three months
- install and maintain the internal plumbing systems properly
- cultivate good habits of tap water use: if the taps has not been used for some time, for instance, after several hours or overnight, run tap water for at least two minutes before use it for drinking or cooking purposes, and save the flushed water for other purposes. If water has been standing in the pipes longer (for instance, over a weekend or after a holiday when the plumbing system has not been used), you need to run the water for longer time.
You can follow the links below to find out more about drinking water and its effects on health.
Water Supplies Department, HKSAR
World Health Organization