A Fine Gael-Fianna Fáil deal on Government has been described as 'an agreement on connivance and cute-hoorism'.
Sinn Féin says the two parties have cobbled together a deal on water that is not listening to the will of the people.
The Dáil will debate the final report of the Oireachtas Committee on the Future Funding of Domestic Water Services in just one hour and 20 minutes on Wednesday evening.
On Tuesday, the report was backed by 13 votes to seven on the committee - with Right2Water, the Green Party and Labour opposing it.
A formal vote to end the current charging regime will take place on Thursday, with Fine Gael and Fianna Fáil to carry it comfortably.
Deputy leader Mary Lou McDonald says the outrage of people on water is not being listened to.
"The connivance by your party, Taoiseach, in your blatant undermining of the democratic and political processes within the Oireachtas.
"The cute-hoorism is, as ever, provided by Fianna Fáil - who have flip-flopped once again".
"Best possible option"
The chairman of the committee, Senator Padraig O'Ceidigh, says the group came up with the 'best possible option' that they could.
"In my view, the committee came up with the best possible option that they could come up with given the various challenges we face.
"We were given a very, very strict time limit - we also had very, very limited resources.
"My fundamental premise here was to create a robust, informed process so that the committee could deliberate on that - and I'm pleased and happy I did that.
'A lot more will actually pay'
Earlier, Fianna Fáil's Barry Cowen said his party had delivered on ending water charges.
"Charges are gone - if you didn't hear me earlier - they're not coming back.
"When all the spin is gone and when all the spin dissipates and fades away, the facts will remain.
"And I have made a firm commitment to everybody that's listening or watching: they won't be receiving anymore bills".
But Independent TD and Right2Water supporter Thomas Pringle said many more than the 8% supposedly using water excessively face a charge in the future.
"A lot more than 8% will actually pay because it's based on a household usage charge, not on a per person per day charge - which is what had been in the previous draft report.
"So that actually significant numbers more of people will actually be levied with charges.
"Of the people who have meters, it could be anything up to 30, 40% of those will be levied with a charge".
Fresh legal advice presented to the committee Tuesday proposed major changes to the report - prompting harsh words between all parties in Government.
Fianna Fáil and Fine Gael have been at odds over the report's recommendations in recent days, with Fianna Fáil warning the water charges issue could trigger a general election.
