The Irish Penal Reform Trust is calling the practice concerning.
37 inmates in Portlaoise are currently 'slopping out'.
A total of 58 prisoners are currently engaging in the process in jails across the country with Limerick prison having the second highest figure at 21.
But the Irish Prison Service says they all have single cells.
However, Fíona Ní Chinnéide, from the Irish Penal Reform Trust, says it's still a concern - especially in the current climate:
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