Shanghai's tap water remains free of the chemical pollutants that temporarily contaminated the water supply in neighboring Jiangsu Province last week, the city's authorities reiterated Thursday, amid continued concern over the issue from local residents.

Local authorities tried to calm fears, saying that even if the city's water supply were to be contaminated in the coming days - the chances of which they described as "slim" - there is enough clean water in reserves to provide to local residents for six days.

"The contamination in Jiangsu was small in scale, and if it really reaches our waters, the pollutants would be quite weak and unable to cause harm to local residents," Chen Wei, director of emergency response for the city's environmental protection bureau, told the Global Times Thursday.

Chen further reminded the public that as an added safety precaution, the city has stepped up inspections of its water supply and will keep the measures in place for the coming days, despite that no signs of irregularities in the waters have been found - and that the pollution would have already reached the city on Tuesday, if it was to have caused a problem, according to experts on the case.

Even in the highly unlikely event that the city's waters were to be affected in the days approaching, advanced purification systems are in place and more than capable of handling the minor case of contamination seen in Jiangsu, local water authorities chimed in Thursday.

About 237 kilometers from Shanghai, Zhenjiang in Jiangsu is where a South Korean cargo ship is suspected to have accidentally leaked phenol, an acidic compound, into the upstream of the Yangtze River last week - prompting residents there to run out for bottled water until Tuesday, when authorities said that its tap water had returned to normal.

A preliminary investigation suggests that one of the valves on the cargo ship was not tightened properly, causing the phenol to leak. Although the "foul-smelling" contamination was never considered dangerous to public health, Zhenjiang officials told local media Thursday that there are plans to sue the cargo ship for contaminating its waters.