Thirty-one students, mainly from Waterford Institute of Technology, were arrested overnight following fights, brawls and disorder in the city centre and a housing estate that is largely rented to students, gardaí said.
Some of the students come from Dublin, Cork and Carlow.
The students have been charged with public order offences.
The events on Wednesday night and early yesterday were linked locally with Christmas partying in advance of the end of term.
Conor Daly, former vice president of the students union, said the behaviour was “totally unacceptable”.
