The independent report revealed that there had been a "serious breakdown in the governance and control framework of NIW in relation to contract approvals".
Regional development manager, Conor Murphy, said this was a "serious matter for those responsible, namely the NIW board and executives responsible for ensuring compliance".
The minister said: "I have today, in light of the findings of the recently completed Review of Procurement Governance in NIW, dismissed the chairman of NIW, Chris Mellor, and a number of his non-executive board colleagues. I have taken this step after a great deal of consideration of all the evidence.
"I intend to take firm action to fully address the recommendations within the report, and have asked the NIW chief executive to work alongside my department in putting in place an action plan to do this."
A statement from Murphy said that chairman Chris Mellor, as well as John Ballard, Ruth Thompson, and Declan Gormley will be dismissed from the board.
The final investigation: Report of the independent review team to the accounting officers of the Department for Regional Development and Northern Ireland, was undertaken to review procurement governance issues within NIW.
It said: "It is clear that NIW has been operating in a complex and dynamic business context since vesting and that the changes in the composition of the Board and senior management have not been helpful in ensuring stability. The recent breakdown in relationships between the NIW Board and its CEO is very serious and must be rectified."
Set up in 2007, NIW is responsible for water and wastewater services in the region but last month, an internal investigation at the firm warned the company to toughen up its procedures in relation to staff taking new jobs outside the organisation, according to the BBC.
This recommendation stemmed from an investigation into a case where company employee took a senior job with an outside company shortly after being involved in awarding them a contract, the BBC went on to say.
Laurence MacKenzie, chief executive of NIW, was reported to have said: "My commitment to ensuring that appropriate financial controls are in place within NI Water is absolute. The review has now issued its report, the minister has considered its findings, and he has now taken steps to implement its recommendations. These include the need to put in place a detailed programme of work to ensure that the control weaknesses are addressed as a matter of urgency."
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