The manner in which Tánaiste Joan Burton was treated by some anti-water charge protesters in Tallaght at the weekend was "totally unacceptable", Green Party leader Eamon Ryan said.

Mr Ryan was speaking at the Mansion House in Dublin at a seminar on the issue of holding a referendum on the public ownership of water utilities.

Mr Ryan said we could not go down the road of “violent protest”. What had happened at the protest in Jobstown was “totally unacceptable and does peaceful protest a disservice”, he said.

Mr Ryan said the refusal of members of the Socialist Party "to acknowledge that fact has done a complete disservice to the tens of thousands of people who marched peacefully on the water charges issue".

He said water was developed not for profit but as a vital service.

He added that the Government was “clearly backtracking” on the issue of the charges and would introduce a lower, flat rate charge system later this week”.

“While it may take some of the immediate heat out of the issue, it risks landing us with the worst of all worlds, where we end up with a permanent flat rate charge and no incentive to introduce the conservation measures which were one of the main justifications of the new charge in the first place,” Mr Ryan said.

He said that in all the the leaks about the form of the new charges there has been “a remarkable silence about whether the Government will agree to hold a referendum enshrining the future public ownership of water supply in the Constitution”.

"Fine Gael representatives have being saying no referendum is needed because no-one is looking for the immediate sale of the company (Irish Water)," he said.

"But allowing the vote is a vital opportunity for the Irish people to decide whether we want to follow the pro-privatisation route that Margaret Thatcher introduced over thirty years ago, or whether we believe that certain key natural resources are managed with more than the profit motive in mind."

Speaking at the same event, Siptu general president Jack O’Connor said the trade union supported the idea of a referendum prohibiting the privatisation of the public water supply.

He said the biggest problem with Irish Water was that it raised "the spectre of privatisation", although the trend globally was now "very much the other way".

He accepted, however, it was unlikely that any of the political parties currently in the Oireachtas would promote privatisation of the public water supply in their election manifesto, although "there may be one in gestation which might".

"Privatisation is more likely to come about as a result of Irish Water becoming insolvent due to its inability to collect its revenues," Mr O'Connor said.

“This could come about very quickly, quite possibly early in the life of the next Government. Those in office at the time would be faced with the cost of taking all the liabilities back on the State’s balance sheet.”

Mr O’Connor said the union was open to discussion about the wording of the referendum amendment.

“In our view it should prohibit the privatisation of the public water supply, ensure that water and sanitation services are maintained in public ownership and control and that the full operation and delivery of these services are maintained within public control.”

On the future of Irish Water, he suggested it could be re-designated as a non-commercial semi-state body or a democratically controlled water authority within the lifetime of the next government.

Other speakers at the event include former MEP Nuala Ahern, Mindy O'Brien of the environmental group Voice and councillor Roderic O'Gorman of the Green Party.