After a deluge that caused the second-longest black rainstorm warning on record, it was water shortages that were concerning legislators yesterday.
The bad news is harvesting Hong Kong's rainwater does not seem like an option, according to Paul Chan Mo-po, secretary for development.
He said huge capital investment in infrastructure, such as pipes, pumps and storage, would be needed.
"It is not cost-effective if the infrastructure can only be used a few times a year during heavy rainstorms," he said in response to a question raised by lawmaker Dennis Kwok Wing-hang.
"Apart from that, the water might be contaminated by bird or animal droppings. The rainwater could only be reused after treatment," he said.
But he noted 30 small-scale rainwater harvesting schemes were in place, providing irrigation or water for flushing toilets.
Up to 80 per cent of Hong Kong's drinking water comes from the Dongjiang, a Pearl River tributary, in a multibillion-dollar deal with Guangdong province. The rest is from local reservoirs.
Legislator Raymond Chan Chi-chuen asked : "Do you have any emergency plan should the Dongjiang be affected by a contamination disaster?"
The minister said the question deserved "thorough consideration", although Guangdong paid serious attention to its water quality and volumes.
He said the province had been studying the feasibility of diverting water from another Pearl tributary, the Xijiang, to Hong Kong as an alternative supply in an emergency.
The minister also said a desalination plant planned for Tseung Kwan O was aimed at producing 50 million cubic metres of water initially. It is projected Hong Kong will need at least 990 million cubic metres of water by 2020.