Fianna Fáil has said the Government has a responsibility to ensure Irish Water comes clean about the spending of €100m of taxpayers' money.
The body now responsible for the supply of water to homes around the country says the money, including €50m on consultancy fees, was spent on establishing the new utility.
It is due before an Oireachtas Committee tomorrow morning to answer questions over how much money has been spent.
Fianna Fáil's spokesperson on the Environment Barry Cowen says the spending we have heard about so far is only the tip of the iceberg.