The Dáil and the Seanad have passed a motion paving the way for the Freedom of Information Act to apply to the new Irish Water utility.
There was cross-party agreement in both houses for the motion, which was tabled by Minister for Public Expenditure and Reform Brendan Howlin.
The act will be applied retrospectively to the new body back to the date of its legal establishment as a subsidiary of Bord Gáis, which was 17 July 2013.
Addressing the Dáil, Mr Howlin said recent developments had highlighted the importance of a high degree of openness and transparency in helping to underpin public confidence in the body.
Irish Water will now be given 30 days to make administrative arrangements to be fully compliant with FOI.
Mr Howlin said he indicated last November it was his intention that Irish Water should be made subject to FOI following the enactment of new FOI legislation.