It follows problems at plants in Ballymore Eustace in Kildare and Gorey in Wexford.
The current arrangements for the safe delivery of drinking water are not working, according to the Environmental Protection Agency.
It'll appear before an Oireachtas committee today to discuss the recent problems at the Ballymore Eustace Plant in Kildare and Gorey in Wexford.
The EPA will say the delay in reporting these incidents to health officials was an 'abject failure' by management.
The watchdog will say audits have found similar events have happened in other parts of the country.
Sinn Féin TD Eoin Ó Broin says immediate improvement is needed
The EPA will call for immediate improvement by Irish Water and local authorities - and Deputy Eoin Ó Broin is backing the call.