Inmates at Pietermaritzburg's New Prison have been without water for the past 10 days, according to a media report.
According to a prisoner who did not reveal his name they were being fed brown bread and the toilets had run dry.
The prisoner told the Witness newspaper he had not been able to relieve himself for five days.
"I've been holding it in for five days now. Prisoners are getting sick.
There are flies and the building is reeking," he said.
According to the report, a prison warden who also spoke on condition of anonymity, said: "If prisoners in Zimbabwe have rioted about bad food, I don't know what these offenders are going to do after just being fed dry bread only."
Correctional services spokesman Thulani Mdluli told the newspaper he could not immediately respond to their questions.