Managers from Irish Water are to appear before the Dáil's Public Accounts Committee on Wednesday.
They will be joined by officials from the Department of the Environment and the energy regulator.
It means senior managers from the new agency will appear before TDs twice in two days.
Committee chairman John McGuinness says he has called the meeting to discuss financial oversight at the new agency.
"We will cover the issues of accountability and transparency and deal with the issue of the need to explain the expenditure to date and the proposed expenditure for the future, relative to the legislation that has been passed," he said.