Northern Ireland Water (NIW) has spent £3.3 million since 2008 on legal fees, according to the Regional Development Minister.
Conor Murphy released the information following a Stormont question from SDLP MLA John Dallat.
NIW said the figure represented value for money for varied and complex work by Scottish law consultants Dundas and Wilson.
Mr Dallat said he wanted to know what the money had been spent on.
"Further questions will be tabled today to dig deeper to establish just exactly what the legal fees were spent on, how much was spent seeking legal advice on how to sack employees, how much on digging NIW out of holes it should never have been in or extricating the company from stupid contracts which tied up millions of pounds of public money for years," he said.
A spokesman for NIW said the costs had to be set against a turnover this year of £350 million.
He said: "The level of fees incurred are comparable with those incurred by other similar organisations and are subject to close scrutiny to ensure value for money is demonstrated at all times."
The total spent went from £489,000 in 2007-08 to £977,000 in the current financial year.
During that period the company has implemented a massive overhaul in how it delivers water and sewerage services. However, it has been criticised for delays in reconnecting people left without water during last December's unprecedented cold spell.
Regional Development Minister Conor Murphy said: "Whilst Mr Dallat is quite entitled to ask questions about expenditure in public bodies including NI Water, I find it rather hypocritical that he should be so vocal in expressing his concerns about NI Water when, at the same time, he has also consistently criticised the ongoing investigation into £28 million of procurement governance issues in NI Water and the removal of four non-executive directors from the board of NI Water."