According to local officials, Atiel Manyok Nhial was collecting water from the Aliet Chok River when the incident occurred on Tuesday evening.
“The incident occurred when the young girl decided on her own to go to the nearby river to fetch water,” said David Atem Matiop, payam administrator.
They say the 13-year-old, who did not know how to swim, was in the company of the other three children, all of whom were younger than her, and thus could not help.
Atem said Atiel drowned after she mistakenly got to the deep end of the river.
“She missed the direction of the shallow part of the river in the name of looking for a cleaner place to get water. She could not save herself there," he added.
In South Sudan, only 10% of the population has access to safely managed and basic sanitation services, according to the WHO and UNICEF.
Drinking dirty and contaminated water leads to water-borne diseases such as cholera and other diarrheal diseases, a leading cause of death among children in the country.