Three million people residing in Chile's capital Santiago were left without drinking water due to "extreme turbidity" of two rivers that supply water to the city.
Because of the problem that started on Saturday afternoon, the Metropolitan Administration decreed a "red alert" for the greater Santiago area, EFE news reported.
Santiago's total population is 6.2 million.
The measure permitted the mobilisation of "all necessary and available resources in order to control the situation, given the extent and severity of water conditions," the national emergency management office said.
"We are activating the emergency plan that we had prepared for such an eventuality. Last year we acquired special ponds for the accumulation of water and we have activated a network of cistern trucks which number around 60," the administrator of the metropolitan region, Claudio Orrego, said.
The Aguas Andinas company, which provides drinking water to the Chilean capital, confirmed in a statement in the early hours that starting Saturday it was cutting off the supply to 27 neighbourhoods out of the 52 in the Santiago Metropolitan Region, without yet knowing when the water could be turned back on again.
"The turbidity of the Mapocho and Maipo rivers reached extreme levels which at 8.00 a.m. on Saturday topped 65,000 UNT (units of turbidity)," the company said.
Waters of the Maipo and Mapocho rivers became extremely turbid due to the bad weather affecting Chile's central area, which could get worse in the coming hours, according to the latest meteorological report.