City Weekend

How safe is Hong Kong’s water?

Direct water usage in the city has increased by 17 per cent per person in the past two decades, prompting safety and environmental concerns

PUBLISHED : Saturday, 01 April, 2017, 5:00pm
UPDATED : Saturday, 01 April, 2017, 5:00pm

Hong Kong began importing fresh water from Dongjiang (East River) in Guangdong, mainland China, during the 1960s after experiencing water shortages.

About 70 to 80 per cent of our fresh water come directly from Dongjiang, and 20 to 30 per cent come from local catchments, according to the government. The water supply agreement with mainland China is subject to continuing reviews. Pressure on the Chinese government to reduce the nation’s water consumption may result in increasing limits on Hong Kong’s supply in the future.

Treatment process There are 21 water treatment works in Hong Kong. The city’s water undergoes a “series of rigorous processes” in order to meet the standards for drinking water set by the World Health Organisation, a spokesman for the Water Supplies Department said.

“Water is dosed with chemicals and mixed for coagulation and flocculation. It then passes to the clarifiers where the settlement of impurities in the water will take place,” he said. “Clarified water then flows into filters for sand and anthracite, to remove 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 water mains, stored in service reservoirs and then supplied to the public.”

Safe to drink? The government maintains that Hong Kong enjoys one of the safest water supplies in the world and that the water in our homes is safe for consumption.

But it advises residents living in older buildings with unlined pipes to replace them with galvanised pipes, copper pipes, stainless steel pipes or polyethylene pipes. The purity of Hong Kong’s water can be affected when it reaches the pipes in a residential block.

Residents can also choose to install filters, but they are not all equally effective and can be expensive, so these should be researched thoroughly before purchase.

Hong Kong’s tainted water scandal in 2015, which revealed that lead levels in tap water at several public housing estates were above WHO safety limits, prompted concerns about pipes in some of the city’s residential buildings.

Average chloroform levels in Hong Kong’s water have remained at less than 50 micrograms per litre, which is far lower than the WHO guideline mark of 300. The government advises that tap water may contain “a small amount of residual chlorine” in order to “keep it free from bacterial infection” as it travels through the city’s extensive water system.

Authorities suggest that boiling the water will cause the chlorine to disappear.

Since 1961, following advice from the Department of Health, the Water Supplies Department has also added 0.5 milligrams per litre of fluoride to Hong Kong’s water in order to help prevent tooth decay.

Meanwhile scientists do not currently believe that drinking water with small traces of dissolved iron can cause harm to people.

Bottled water A 2014 report by market research company MarketLine found that 418.3 million litres of bottled water – including still, sparkling and flavoured – were sold in Hong Kong in 2013, according to non-governmental organisation Civic Exchange.

But environmentalists warn buying bottled water is damaging for the environment, as it takes an average of three litres of water to produce one bottle of drinking water. Meanwhile, Hong Kong throws away four to five million plastic bottles every day, according to the Environmental Protection Department. Scientists have revealed how humans end up ingesting tiny plastic particles by consuming animals that have inadvertently eaten plastic.

Moreover, US-trained dietitian Tracey Pui, who works for the Tetra Nutritional Consultation Centre in Hong Kong, estimates that for every dollar the city spends on bottled water, 99 cents goes towards the manufacturing process of the product, rather than the water itself.

Water consumption Direct water usage in Hong Kong has increased by 17 per cent per person in the past two decades.

It is estimated that each Hongkonger has a water footprint of about 1,700 cubic metres per year – half of which is attributed to meat consumption and just 3 to 4 per cent attributed to domestic uses such as drinking or bathing.

Domestically, Hong Kong’s water usage rate is high at 220 litres of water consumed per capita each year – surpassing the global average of 170 litres.

Cost The city’s water tariffs are relatively low compared to other major cities in the world, particularly given that its GDP is relatively high.

Beach life The Environmental Protection Department regularly assesses the water quality at all of the main beaches in Hong Kong.

As of March this year, the water at Big Wave Bay, Clear Water Bay, Deep Water Bay, Discovery Bay and Shek O were all graded as ‘good’.