Shanghai authorities have dispelled rumours of water shortages and quality issues and reassured citizens supplies remain “normal”.

Residents had rushed to stockpile bottled water amid rumours that the city was facing a supply crunch brought about by a long drought across the Yangtze river basin this year, as well as a salt tide intrusion in the river's estuary.

The backflow of sea water into Shanghai's depleted reservoirs began in early September, and the city's water supply firms are closely monitoring the situation and "scientifically" making adjustments to water flows, the city government said on its official WeChat channel late on Tuesday.

"Tap water production and supply are normal, and water quality standards have been reached," it added.

Shanghai experienced a wave of panic buying earlier this year amid fears of food and water shortages brought about by a city-wide Covid-19 lockdown that eventually lasted more than two months.

Residents were also alarmed by a series of announcements on Tuesday saying that water supplies would be cut off in some parts of the city, but a government spokesperson said on its WeChat channel that these were "routine" overhauls mainly aimed at cleaning out pipelines.

Precipitation has dropped by as much as 60 percent in some parts of the Yangtze river basin since July, forcing the authorities to deploy cloud-seeding rockets and dig new emergency wells to ensure crops were sufficiently irrigated ahead of the autumn harvest.

Poyang Lake, a major Yangtze flood outlet, is at its most depleted level on record, and several reservoirs in central China were reported last month to be at "dead pool" status, meaning they did not have enough water to dispatch downstream. (Reuters)