When contacted by the last week for an interview for this article, Wong said: "Not now. I am going to have a press conference soon. And after that, I am going to meet officials and later in the evening, we will visit estate tenants."

With the district council elections in November and the Legislative Council poll next year, the tainted water saga, which has been dubbed "Hong Kong water-gate", makes this the prime time for politicians to try to shape what voters think of them.

Almost all political parties, be they pro-government or otherwise, are now jumping on the bandwagon and are testing water samples from as many private and public estates as possible.

As such, the saga is more about politics than health - with the risk of poisoning thought to be low. So it perhaps comes as no surprise that Wong, a lawmaker since 2012, has become a target of criticism by rival politicians.

Chief Executive Leung Chun-ying's close aide, government information coordinator and former Democrat Andrew Fung Wai-kwong, also weighed in, criticising Wong for politicising the issue and deliberately delaying the release of water test results until after the rejection of the government's political reform package last month.

Wong argued it took time to verify the test results and await the government's response, although one case had been detected in the first round of tests in early May.

"It would be irresponsible if we made public our results with only one isolated case [of lead contamination]," Wong said yesterday during RTHK's programme.

Lead is a heavy metal which can enter the body by ingestion, inhalation and skin absorption. Long-term exposure to it in excessive amounts may result in anaemia and brain and kidney damage.

The World Health Organisation guidelines for drinking water quality set a value of not more than 10 micrograms a litre for the metal. Government officials say lifetime consumption of water complying with the guidelines will not pose significant health risks.

Hong Kong Institute of Utility Specialists president Wong King and former Chartered Institute of Plumbing and Heating Engineering chairman Hugo Kan Kwok-leung also criticised Helena Wong for amplifying the lead water problem, while Society of Hospital Pharmacists president William Chui Chun-ming also said there was no need for the public to panic.

Despite the criticism, Helena Wong is still getting the upper hand. Leung yielded to her demand and ordered a commission of inquiry to investigate the scandal. Wong was also quick to criticise Leung for not doing enough and was pushing for another investigation by Legco itself.

The saga was brought to the attention of various political parties earlier this year in an anonymous letter of complaint, according to Wong's party colleague and fellow lawmaker Albert Ho Chun-yan.

Ho said in an online radio show last Tuesday: "Many parties got the anonymous letter as far as I know - the Democratic Alliance for the Betterment and Progress of Hong Kong, the Federation of Trade Unions, the Association for Democracy and People's Livelihood, the Democratic Party, you name them … Helena was very serious about it and she found several laboratories to test the water samples."

This appeared at odds with what Wong had previously told the press: that it was she who took the initiative to test water in estates in Kowloon West.

"It will be easily forgiven, or forgotten. Helena has shot to political stardom," said Dr James Sung lap-kung, a political scientist at City University.

She was not a particularly well-known figure among the 70 lawmakers in the legislature. In an April poll by the University of Hong Kong, only seven of the 702 respondents named her among the top 10 legislators they were most familiar with, compared with 278 who pointed to "Long Hair" Leung Kwok-hung of the League of Social Democrats.

Wong is the party's spokesman on food safety and environmental hygiene. She also takes charge of education, home affairs, women and gender issues, animal rights, youth and family policies in the party, and is a member of its central committee.

Before "water-gate", she was best remembered for a series of blunders during her early days as a lawmaker.

In 2012, she was blamed for a surprising abstention that allowed the Legislative Council House Committee to veto a pan-democrat's attempt to force a debate into allegations that Franklin Lam Fan-keung had profited from insider information on new stamp duties picked up in his role as an Executive Council member, from which he later stood down.

Wong said she had wanted to support the motion but mistakenly pressed the "abstain" button. She later had to join a session to learn how to use the Legco electronic voting system.

In 2013, at a meeting of the Independent Police Complaints Council, she repeatedly called on the police to submit reports detailing illegal parking cases in different districts. She was at last stopped by council chairman Jat Sew-tong, who told her that illegal parking data was outside the council's terms of reference.

"Changing people's deeply held views is difficult," said Dr Sung. "But if Helena can keep up her good work in the water saga, she and even the Democratic Party can win back voters' support that has been waning after the party's controversial involvement in the Occupy protests and the rejection of the political reform package."

Although she is still a greenhorn in Legco, Helena Wong is not new to politics.

She joined the Hong Kong Christian Council in 1984, working on political policies and social affairs. She was a founding member of the United Democrats, which became the Democratic Party in 1994.

She co-founded the Hong Kong Christian Institute in 1988 as an ecumenical Christian non-governmental organisation outside the institutional constraints of the church. She also chaired the Hong Kong Women Christian Council from 1999 to 2002.

She has lectured at Polytechnic University since 1999, with a focus on Hong Kong and mainland China, and women's issues.

A feminist, she decided not to be a traditional housewife. In an interview in 2012, she said: "Long ago, I decided not to get married early and would use more time to study."

She went abroad to further her studies when she was 30. She finally married Dr Shae Wan-chaw, an associate professor at PolyU, in 2001, at the age of 42. At the age of 53, she became a lawmaker.

HELEN WONG PROFILE

Education

• Chinese University, MPhil (government and public administration)
• University of California Los Angeles, PhD (political science)

Political career

• 1984: Hong Kong Christian Council
• 1988: Hong Kong Christian Institute
• 1989: Hong Kong Democratic Foundation
• 1990: United Democrats of Hong Kong
• 1994: Democratic Party
• 1999-2002: Hong Kong Women Christian Council, chairwoman
• 2004-05: Hong Kong Christian Institute, chairwoman
• 2011- present: Independent Police Complaints Council
• 2012-present: Legislative Council