Empathy and transparency from the government when it responds to situations are key, a lawmaker has stressed, following a safety scare over the discovery of bitumen in the freshwater supply at two Fanling housing estates.

The DAB's Edward Lau on Wednesday also said a series of government work has "largely" allayed the concerns of residents at Queen's Hill Estate and Shan Lai Court over black particles found in tap water, but noted that the authorities should continue with their cleaning work.

On RTHK's "In the Chamber" programme, he said there were lessons to be learnt from this incident.

"Even if the government cited science to say the water is safe, I believe that residents may not feel comfortable about drinking it," Lau said.

"The government needs to have empathy and understand residents. It also has to be prompt. Once the government gets hold of information, it should be transparent and make announcements, so that it can take the lead in the whole issue."

The government earlier said it would replace a 400-metre-long water pipe lined with bitumen within this year as part of a response plan.

The legislator said he understood that the authorities would have to carry out preparatory work before the actual replacement of the pipe located beneath a stretch of road, to ensure traffic and water supply were not affected.