Time to overhaul Hong Kong’s water supply system, as lead contamination is only part of the problem
Asit K. Biswas says the contamination found in Hong Kong’s tap water only points to mismanagement
According to the World Bank, Hong Kong’s per capita gross domestic product is US$40,169. This is higher than Japan’s, Italy’s or Spain’s, and only 5 per cent less than that of France. However, even for such a developed region, its water management practices are light years behind a place like Costa Rica, whose per capita GDP is about one-quarter that of Hong Kong.
During the past fortnight, Hong Kong’s water supply system received a double whammy – the first punch being excessive lead content found in drinking water at a growing number of housing estates, and then legionella bacteria found in one location.
Let’s assess both short- and long-term implications of these developments and offer a possible road map to move Hong Kong’s water management system from the Third World to the First World.
Normally legionella outbreaks have been traced to humidifiers of air conditioning systems, hot and cold water supply systems and industrial heating and cooling processes. Transmission is primarily by inhalation of aerosols containing the bacteria. We have to wait until the investigations are completed, but it is unlikely that the city’s water system is directly responsible for this outbreak.
While legionella outbreak is an immediate health threat, higher concentration of lead is a different story. It is difficult to decide what the highest permissible level of lead in drinking water should be for health reasons. The lead level in the United States is 50 per cent higher than in Europe or Hong Kong. The European drinking water directive of 1980 allowed five times as much lead as it does now. In 1993, the World Health Organisation amended its guideline value to a maximum of 10 micrograms per litre, and the European Union adopted that standard in December 2013.
What needs to be investigated in Hong Kong is how long this high level of lead has been in the water, how it got into the system, and why the Water Supplies Department’s surveillance system failed to identify the problem promptly. Also, are there other pollutants in the water system?
If this high level of lead has been in the system for one to three weeks, it should not be a serious problem. However, if lead has been present for months or years and was undetected, and if there are other hazardous contaminants in water, their potential synergistic adverse health effects need to be carefully investigated.
