Sinn Féin has launched its Private Members motion to abolish water charges.
The party's spokesman on Housing, Planning and Local Government, Eoin Ó Broin, said it would cost €140 million to abolish the charges.
He said the cost would be included in his party's Budget plans.
Mr Ó Broin added that Sinn Féin now favoured refunding those who had paid the charges, which he said would cost between €140m to €160m.
However, he said this would not be included in the Sinn Féin Budget submission as a decision would not be made by the Government on the matter until next year, adding that they would then have a clearer picture of the costs.
He said Sinn Féin had previously supported an expert commission to look at water, but this had a much wider remit than the one established by the Government.
Mr Ó Broin said the new commission on water charges was a "complete waste of time".
Addressing Fianna Fáil deputies, Mr Ó Broin called on them to support the Sinn Féin motion.
He criticised the party's previous position on charges, saying the party had finally come around to Sinn Féin's way of thinking.
Mr Ó Broin accused Fianna Fáil of keeping their options open.
He said the majority of TDs and the electorate wanted the charges scrapped.
Sinn Féin TD Louise O'Reilly told the House that Fianna Fáil had more positions on water than the "Kama Sutra".
Meanwhile, Minister for Housing, Planning and Local Government Simon Coveney accused Sinn Féin of "flip-flopping" on water themselves.
He defended the make-up of the new commission and thanked all those who had made submissions to it.
He said the Oireachtas would make a final decision on water charges by March 2017.
Minister Coveney said they would have to make a serious decision at the end of the deliberative process and said that he wanted to re-iterate his belief in the "polluter pays" principle.
Mr Coveney said those who are in group water schemes and private wells end up paying a disproportionate price.
He said Irish Water's key objectives was eliminate risk for 800,000 people on deficient supplies, ending boil water notices and reducing leaking from 49% to 30%.
He said deputies would need to ask if central taxation could meet these needs, saying the previous funding model did not work.
Mr Coveney appealed to TDs to give the new commission the further six months required, and said that Ireland was top of the list of countries with no security of water supply.
Fianna Fáil's Barry Cowen said Sinn Féin's position was more like "Houdini" than "Kama Sutra".
Mr Cowen said Mr Ó Broin had once favoured a commission on charges, but now that he has one he does not want it.
Mr Cowen said he would vote against the Sinn Féin motion which he said had no legal basis.
Social Democrat TD Catherine Murphy said water was the straw that broke the camel's back for people who had endured so many extra charges.
Ms Murphy said people were then also rightly concerned about the awarding of contracts to Siteserv.
Green Party leader Eamon Ryan said his party believed in water as a right and it believed people should have a basic allowance.
But, he added, there should be a charge, to raise revenue to create water services and to stop people wasting a precious resource.
