The water supplies of 980 kindergartens are to be tested for lead contamination, Chief Secretary Carrie Lam Cheng Yuet-ngor confirmed at a Legislative Council meeting on Tuesday.
Full-time kindergartens as well as those that are also open on Saturdays will be the top priorities.
The announcement came despite the Secretary for Education Eddie Ng Hak-kim saying last week that the government would not test water supplies for schools.
Lam said the government hoped to finish the tests for kindergartens in less than six months.
After testing water supplies in kindergartens, the government will do the same for some 80 primary and secondary schools built after 2005.
The house committee of LegCo rejected a motion supported by 27 pan-democrat lawmakers to urge the government to propose a clear plan and timetable to handle the lead contamination scandal in 14 days, by 20 yes votes to 25 no votes, at the end of the meeting.
In the last two weeks, four primary schools have found excessive lead contents in water samples.
The first case of lead contamination was discovered in July when a water sampling investigation was conducted at Kai Ching Estate in Kowloon City. Eleven public housing estates and seven educational institutes have been affected to date. The majority of these housing estates were constructed in the last decade.
An independent commission chaired by a judge was appointed to investigate the lead-in-water scandal. The commission is expected to report in nine months.