Authorities say it is now Ireland's "established practice" to impose the charges
The European Commission has stated there is no way for Ireland to legally abolish its system of water charges.
Authorities in Brussels say it is now clearly Ireland's "established practice" to impose domestic water charges.
In a reply to a written question from MEP Marian Harkin, it said Ireland made a clear commitment to implement the charges under a plan submitted by former environment minister John Gormley in 2010.
It says Ireland's derogation against water charges was lost at that point, and there is now no way under European directives that a previous practice can be restored.
"Ireland adopted its river basin management plans in July 2010. There is no record of a decision in those plans not to apply the provisions of Article 9(1)", the commission says.
"On the contrary, in the said plans, Ireland made a clear commitment to set up water charges to comply with the provisions of Article 9(1). Ireland subsequently applied water charges and the Commission considers that the Directive does not provide for a situation whereby it can revert to any previous practice," it adds.
Minister for European Affairs Dara Murphy told Newstalk Lunchtime this is a welcome process.
While Sinn Féin MEP Lynn Boylan says she has requested an "urgent meeting" with the EU Commission following the ruling.