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.

Dublin Jersey Among Tributes To Ryan Weir Gibbons - Death “Unnecessary And Tragic” Says Priest
Three Decades Later, Search For Answers In Jo Jo Dullard Case Continues
Kildare County Council Targets Unused Housing Sites With Planning Permission To Speed Up Construction
EU Environment Commissioner Visits Kildare Farm Ahead Of Nitrates Derogation Talks
Defence Forces Conduct Readiness Exercise At Whitewater Shopping Centre In Newbridge
Call For Sanitary Bins In Men’s Toilets To Support Prostate Cancer Survivors
Own-Brand Foods Often Produced By Same Factories As Big Labels, Says Money Doctor John Lowe
Kfm Strengthens Position As Kildare’s Most Listened-To Station, According To Latest Ipsos/MRBI Report