Taoiseach Enda Kenny has said the issue of water metering is one for Irish Water.
He said Ervia Chief Executive Michael McNicholas made clear this morning the difference between the estimate of the cost of water metering and formal tender.
Mr Kenny said the important issue about metering is that it allows people to conserve water and to detect leaks which, he said will lead to further savings and less water wasted.
Earlier, Mr McNicholas defended the underestimation of the cost of installing water meters.
Speaking to RTÉ's Morning Ireland, he said the initial figure of €431.56m provided was not a final costing figure.
RTÉ News revealed yesterday that the figure now stands at €539m, which is €107m higher than the original detailed estimate provided by Bord Gáis to the Department of the Environment.
Mr McNicholas said Bord Gáis would only ever have been able to provide accurate costings after the job was tendered to market and costings had been provided by contractors.
He said: "There's only ever been one budget for the metering programme and that is the budget that was finalised in May 2013 for €539m.
"In late 2012, the Department [of the Environment] asked Bord Gáis to put together an estimate of what they felt the overall metering would cost, and came up with an estimate of €430m.
"That is an estimate and it was very clear when they came up with that estimate that the final figure or any final figure for this project would only arrive as a result of going to the market and tendering."
Minister for Transport Paschal Donohoe has said he is pleased that Mr McNicholas has given assurances that any work carried out in Irish Water was done with the strictest regard to corporate governance structures.
Speaking in Galway, the minister said it was a matter for opponents of plans to water charges to decide whether they maintained protests in the coming weeks.
He said he hoped more people would register as a result of last week's announcement on charges.
Minister Donohoe reiterated the need for more funding to improve the water infrastructure.
This evening, the Taoiseach said people are perfectly entitled to peaceful protests in relation to water charges and that is part of our democracy.
However, he said he believes the concerns raised by people of certainty, clarity, fairness and affordability have now been addressed by the Dáil announcements last week.
Around 200 people protested against water charges outside the Green Hills Hotel in Limerick where the Taoiseach Enda Kenny is addressing a Fine Gael meeting.
There is a strong Garda presence in the hotel grounds where the protesters have gathered.
Around 45 protesters gathered earlier at Ballymaley Industrial estate outside Ennis as the Taoiseach visited TTM healthcare.
In Dublin earlier today protesters attempted to block the installations of water meters.
Water meter installers being prevented by protesters from entering the Woodlawn estate in Santry / Coolock today pic.twitter.com/ELWb88KCns
— Peadar Mac Gaoithín (@MacGaoithin) November 24, 2014