Northern Ireland Water has spent £3.3m 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 £350m.
He said: "Legal fees paid by Northern Ireland Water reflect the varied and often complex nature of the operations undertaken. These include its legal and regulatory obligations as well as necessary work that needs to be undertaken on its behalf by its legal advisors on various issues."