Leo Varadkar has reopened the controversy over the future of Irish Water, warning that "sooner or later" householders will have to pay charges.
The Social Protection minister criticised Fianna Fail for their focus on getting rid of charges in the talks leading to the minority government deal, saying he believed other issues - such as Health - were more important.
"I just think that they got themselves on the hook during the election campaign," Mr Varadkar said.
"I've no doubt that sooner or later in Ireland people will pay domestic water charges. It might not be in a year's time or two years' time or nine months' time. I don't know when, but that's the direction of travel in the world and that's European law," he added.
Mr Varadkar said there is a compelling case for paying charges. "It's the best way to ring-fence money and invest in infrastructure and the best way to encourage people to conserve," he told Newstalk Radio's Pat Kenny.
In relation to his own brief, Mr Varadkar said one of his priorities was examining ways to get more people to get private pensions. He said many countries were introducing compulsory schemes or automatically enrolling people who must choose whether to opt out.
He said the age at which pensions are paid out is going up. "It's 66 now. It'll be going up towards 68 over the next couple of years and that is the right thing to do... People are living 20 or 30 years after they retire which is a great thing on one level but is not sustainable from a pensions point of view so we will, over time, have to increase the pension age," Mr Varadkar said.
The Dublin West TD is viewed as one of the main contenders to take over from Taoiseach Enda Kenny when he steps down as Fine Gael leader.
He said it's up to Mr Kenny when he decides to go. "I certainly don't think he should set a date or anything like that, because once a politician does that you're a lame duck. That happened to Tony Blair and that happened to Bertie Ahern".
"And I also don't think it should necessarily be any time soon."
He insisted his party was more concerned with providing "good government" than planning when Mr Kenny should step down.
On the row over the location of the new children's hospital at St James's, the former health minister said there was no perfect site.
"But when people actually set foot in that place and when they see it in 2020 or 2021, people are going to wonder why we didn't build it 10 years ago," he added.