A detainee at Darwin's problem-plagued Don Dale Youth Detention Centre has suffered a fractured arm while being taken to use the shower.
The incident happened on the same day some cells were left without water after an excavator damaged a water pipe while demolishing a building that was destroyed by fire during a riot earlier this month.
"As a result, water supply to some areas of the centre were interrupted including some accommodation areas," a spokeswoman for the Department of Territory Families said.
"Where this occurred alternative arrangements were made for detainees to ensure they had access to drinking water and toilet and shower facilities."
The Department told ABC an investigation into the incident had been launched.
"The young person suffered a fracture to their arm and was treated at the hospital and returned to Don Dale Youth Detention Centre later that night," a spokeswoman said.
"An investigation is conducted into any incident that occurs at the centre."
It is unclear whether the detainee would ordinarily be escorted to the shower.
On Friday, eight detention centre staff called in sick, causing programs provided by six external organisations for detainees to be cut short.
"Staff sick leave can impact operation of the facility," the spokeswoman said.
"As the security and safety of young people is our priority, this needs to be managed appropriately.
"As a result of reduced staffing levels the activity program was reduced."
A spokesman for the Northern Territory Children's Commissioner said the office was aware of ongoing problems at Don Dale since the riot.
He said staff continue to monitor the facility but he was unable to comment further on operational matters involving Territory Families.
Twenty-six boys and one girl are currently detained at the Darwin facility.
Another 15 detainees, including one girl, are held at the Alice Spring Youth Detention Centre.
