The Chief Executive of Irish Water's parent company, Ervia, has told an Oireachtas committee that the move to a single public utility will free up €70m a year in operational savings and efficiencies.

However, Mike Quinn also told the Committee on Housing, Planning and Local Government that, with an estimated overall infrastructure deficit in excess of €13 billion, it will take several investment cycles to address this.

Mr Quinn said the company has written to Minister Eoghan Murphy to inform him of the Ervia board's intention to not renew the Service Level Agreements with the 31 local authorities after 2025.

He said that, while there had been very considerable progress in the transformation of public water services since 2014 by Irish Water, working under an SLA model had particular limitations.

"We suffer inconsistent customer service outcomes due to the different work practices and the lack of consistent reporting on service responses.

"We incur substantial costs in fragmented management and workforce structures across 32 organisations which can result in delays and operational complexity, with no clear accountability," Mr Quinn said.

Several committee members expressed concern about the impact on local services of a move away from SLAs, given local knowledge of the system.

Solidarity People Before Profit TD Mick Barry told the committee that any introduction of water charges by the back door would be resisted by communities throughout the country.

He also asked representatives of Irish Water how they intend to introduce excessive charges when 42% of households are not metered.

The company's Managing Director Jerry Grant said this is currently under consultation, but in broad terms 80,000 people had indicative leaks in their service.

He said of 4,000 houses it is in direct contact with, each uses an average equivalent of 35 houses, and "the impact of that is that their neighbours are suffering low pressure".

He said that for homes without meters leaks are followed up in the same way.

Mr Barry also queried a charge of €100 for "incorrect call outs", describing it as blatant discrimination against low income families.