Hundreds of thousands of people are going without running water for two days at a time in Puerto Rico, as authorities in the US territory take drastic measures to combat a severe drought.

Many households on the Caribbean island have been split into two groups - with each having their water supply shut off for 48 hours on a rotating basis.

Residents in the capital, San Juan, where the taps were turned off on Friday, decried the rationing. Officials have not said when the measure will end.

Most of Puerto Rico is facing moderate to severe drought conditions, according to the US Drought Monitor, which has been compounded by long-term issues with the island's infrastructure.

Puerto Rico's water authority says about 65% of the water it produces is lost or goes unbilled, much of it through leaks and ageing pipes, according to the BBC's US news partner CBS.

The island's Governor Jenniffer González has acknowledged these issues, but says rationing was implemented due to the weather, which has left the crucial Carraízo reservoir depleted.

Puerto Rico experienced its driest July on record, with 68% of the island currently facing drought conditions.

Seven regions usually served by the reservoir have been affected, with 180,000 properties subject to rationing, the government said.

González said the decision was taken "after carefully evaluating the current conditions of the Carraízo reservoir in conjunction with weather forecasts".

"This situation is beyond our control," she said in a statement. "It is the result of the weather conditions we have been facing, which experts had warned about weeks ago."

As the mains outages take effect, people have been queuing at water tanker trucks sent to affected regions to fill up large bottles.

"It's unbelievable to live through this today," San Juan resident Gloriany Baba told CBS, describing the conditions as "brutal".

But there is some confusion in the territory as to which households and businesses will be affected and when.

The Morcelo area, south of San Juan, was promised water on Friday, with the supply set to be shut off on Sunday, after the first 48-hour period had ended. But residents have told local media that running water was not available.

"People are uncertain because they know we're in the 48-hour window where we're supposed to have drinking water," community leader Rubén Torres told newspaper El Nuevo Dia on Saturday.

"What's happening? The first 24 hours have already passed and the water hasn't arrived."

As well as degraded infrastructure and a lack of rain, experts have also pointed to too much sediment in resevoirs as a factor in the water crisis.

Water rationing measures have been tried previously in 2020 and 2015, when some 400,000 households only received running water every third day.

Puerto Rico has previously been shaken by the kind of extreme weather events scientists say are more likely due to human-induced climate change.

The island's electricity grid was devastated in 2017 by Hurricane Maria, which caused thousands of deaths. Scientists say the extreme amounts of rainfall it brought was made more likely due to climate change.

González also told CNN there were more than 1,000 wildfires currently burning in Puerto Rico, and that rain could return when a cloud of Saharan dust drifts away from the Caribbean.

"It's a difficult situation," she said, adding that the US federal government was "helping us out", without elaborating.

BBC News has approached the US disaster agency Fema for comment.