originally published on July 16, 2015

As the lead-in-water crisis spreads to more public housing estates in Hong Kong, the South China Morning Post’s BEN WESTCOTT and SAMUEL CHAN spoke to experts and reviewed laws to answer the issue’s major questions.

The fear over tainted water in Hong Kong has thrown hundreds of residents’ lives into chaos and left thousands more wondering if their water is safe to drink.

The discovery of lead at levels up to three times higher than the World Health Organisation’s recommended level in drinking water from a public housing estate in Kowloon has grown to affect more than 1,500 local households.

Elderly Hongkongers have found themselves carting heavy containers of water to their flats, while the housing minister has been forced to apologise over confusing statements on the crisis.

Parents and homeowners have been left with dozens of questions – can I drink the water in my flat? Should I boil it? Will any lead in the water affect my children? Who is responsible for the affair?

The bad news for families who are concerned about their water quality is that lead can be extremely dangerous to drink, particularly for children who will be affected by smaller quantities than adults.

But that isn’t the whole story. There are ways you can be sure your water is safe to drink.

Water quality testing is available at certain laboratories in Hong Kong for people concerned about their tap water, and certain filters can be bought that will remove lead from your water supply.

Compared to other countries, Hong Kong has very strict guidelines about how much lead can be in tap water. It adheres to the World Health Organisation allotment of 10 micrograms per litre, less than in the United States or on the mainland.

Once the water has entered the private pipes in buildings, however, it is no longer the responsibility of the government and can become exposed to a range of chemicals, metals and bacteria from poorly maintained pipes.

How safe is it to drink Hong Kong’s tap water?

Hong Kong’s water, when it reaches the city’s water mains, is completely safe to drink, and complies with the WHO’s strict standards.

The problems start when it hits the pipes inside buildings both public and private across the city, which might not be regularly maintained and aren’t directly regulated by the government.

Once it has contact with these pipes, the quality of water can change dramatically.

How does Hong Kong’s limit on lead in tap water compare internationally?

Hong Kong allows up to 10 micrograms of lead per litre of the city’s tap water, the same as the WHO standard. This is the limit also used by Europe, Australia, Taiwan, Japan and Singapore.

The United States, however, will allow up to 15 micrograms of lead, while the mainland has a limit of 50 micrograms per litre.

Does lead affect people of all ages equally?

No. Young children in particular will be very vulnerable to damage from lead poisoning. Even smaller doses that wouldn’t affect an adult will have a serious effect on young people, including unborn children.

According to the US Environmental Protection Agency, over-exposure to lead can leave children irreversibly damaged both physically and mentally.

How much lead is too much?

Recommendations vary from country to country – the WHO recommends no more than 10 micrograms per litre of drinking water, while regulators in the United States allow 15 micrograms. Water samples from the Kai Ching Estate contained between 10.8 and 35.1 micrograms per litre.

But some experts said drinking water would need much higher concentrations of lead than this to become dangerous . It is also safe to shower and bathe in water with higher levels of lead concentration than is safe to drink.

Should I boil the water or get a filter to remove the lead?

Boiling the water will have no effect on the amount of lead and could in fact increase the concentration, as some water will evaporate, leaving the heavier lead behind.

Certain filters can remove lead from your water, but do research before you buy. Filters can be expensive and not all of them will be equally effective.

What kinds of buildings are most at risk?

Lead is no longer used as a component for making water pipes in post-war construction in the city, so lead or other harmful materials should not be present unless substandard construction supplies have been used. Under normal circumstances, lead will not appear as the pipes age.

The question may instead be whether the contracted developer of your unit block or house has used materials that adhere to the city’s safety standards.

How can I make sure the pipes at my housing estate or house are safe?

Take two water samples of 300ml each – one taken immediately after turning on the tap and the other taken two to eight minutes afterwards. Any sediment present in interior pipes should be shown in the first sample while the second sample is to get as close a result as possible to the water coming directly from the filtration plant.

Where can I take samples for testing and how much will it cost?

One major testing lab, the Hong Kong Standards and Testing Centre, introduced a test for lead in a single water sample on Tuesday for HK$250, if one takes the samples to the centre.

The water container and tap nozzle should be disinfected to avoid any contamination that may interfere with the test results.

Results will be available in two working days.

If I live in a rented village house, which is not managed by a company, what can I do to ensure the tap water is safe to drink?

Taking your home water samples for testing should be the first step.