Aid workers say they have improved access to Bentiu IDP camp owing to the repair of an Mi-25 helicopter, which has been the main supply line to the Bentiu site.
The helicopter is carrying a backlog of supplies, including critical sanitation equipment.
The IDP camp was flooded this week owing to heavy rains on 5 October. This caused many latrines to collapse. Mechanical pumps are being used to pump floodwaters out of the camp.
More than 47,000 people live under UN protection at the camp in Bentiu, according to the latest figures from the UN Mission in South Sudan (UNMISS).
They cannot leave the site in spite of flooding because they fear being targeted in racial killings.