Taoiseach Enda Kenny has warned rival parties it would be "a costly and seriously historic mistake" to scrap Irish Water.
The embattled Fine Gael leader made the claim in his first public comments since the weekend's devastating election results for his party and as a senior Government minister last night said Fine Gael is open to discussing the utility's future.
Speaking at a press event at Collins Barracks in Dublin City, Mr Kenny said the retention of Irish Water remains a "fundamental" issue for his party.
However, he declined to say Agriculture Minister Simon Coveney was wrong to say its future could form part of talks with Fianna Fáil or other parties.
"Simon was correct in what he said, that Fine Gael wants to move on and form a government. Part of that is to listen to like minded parties.
"But I want to say in respect of Irish Water, I think it would be a seriously costly, seriously historic mistake to remove it.
"It's a fundamental issue for Fine Gael," he said, adding people should continue to pay their bills.
Irish Water is set to become a key post-election negotiations issue over the coming weeks with some parties saying it is necessary and would cost too much to dismantle and others saying the vote shows the utility has no mandate.