SIPTU has warned that there are major question marks over the use of Public Private Partnerships in the water services industry.
The union's Michael Wall told an Oireachtas Committee that it had studied over 40 reports about similar mechanisms abroad and all had concluded that the partial privatisation model was not suitable for water services.
He said handing over water services to the private sector over 20 years would be a 'fundamental mistake'.
Dr Eoin Reeves of the University of Limerick, who has studied PPPs, said privatisation of water services abroad had been unsuccessful and many were reverting to a public model, referring specifically to Paris as an example.
The committee was told that of the 109 PPPs that are in the procurement process at the moment, 66 are in the water services sector in the areas of water provision and waste water treatment.
Socialist TD Clare Daly said it was clear that the practice of forcing local authorities down the road to privatisation was costing the State much more than leaving it in the hands of the council workers who had decades of experience at the coalface.
Denis Naughten TD, who lost the Fine Gael whip last year, said he believed PPPs in water services amounted to 'failed developing world policies' being implemented in Ireland.
He said he had seen situations where local authorities were forced into taking the cheapest contractor on offer and were now spending millions bringing them through the courts to get them to carry out repairs.