Irish Water has said all its contracts are fully compliant with public procurement rules.
In a statement, the organisation said Bord Gáis and Irish Water had been scrupulous in the awarding of contracts.
To ensure value for money and transparency, the agency said, all contracts were awarded in line with the guidelines set out at EU level for public sector procurement.
The statement is in response to claims that a number of Irish Water contracts never went to tender.
Meanwhile, Irish Water's CEO John Tierney will today be asked to explain how the agency spent €50m on consultants last year.
Mr Tierney will appear before the Oireachtas Environment committee to discuss spending and set up costs.
Tomorrow evening, he will appear at the Public Accounts Committee to discuss ways for TDs to scrutinise Irish Water's spending in future.