The expert said Hong Kong's COVID-19 struggle has added to the water crisis of the city.

"The suspension of many economic activities in Hong Kong due to Covid-19 over the past two years has not lowered our fresh water consumption. On the contrary, we set a new record in water usage last year,"  Edwin Lau Che Feng, executive director of The Green Earth, worte in the South China Morning Post.

"The city consumed 996 million cubic metres of water in 2019, the year before the outbreak of the pandemic. This figure increased to 1,027 million cubic metres in 2020 and 1,055 million cubic metres in 2021. Both levels are the highest on record, largely because of an increase in water use for washing and cleaning," he said.

He wrote, "This worrying scenario is exacerbated by the sharp drop in the amount of water collected in our reservoirs. In 2016, 385 million cubic metres of water was collected by reservoirs. But, last year, that figure was only 202 million cubic metres, representing a 47.5 per cent drop over the past five years."

He said Hong Kong is getting hotter and dryer.

"The total rainfall in 2021 was 2,307.1mm, which is 4.6 per cent lower than the 10-year average of 2,414.5mm. With the combined challenge of hotter temperatures and reduced precipitation threatening Hong Kong, we must use every opportunity to lower our water consumption. One important step is to speed up the repair of leaking public and private pipes to minimise water wastage," he said.

He said: "Climate change means water is an ever more precious resource. At the moment, Hong Kong residents pay a relatively low water tariff. But to prevent that from rising sharply and water rationing becoming a regular event in the city, all government departments, businesses and individuals need to pay much greater attention to water conservation."