Mr Roche plans to overhaul the system, introducing guidelines this autumn to remove all "ghost voters" from the register.
Mr Roche said the situation had been tolerated for too long, and laid the blame squarely on local authorities. They had contributed, he said, to a situation where there are more than 3 million voters on the register while only 2.7 million people are eligible to vote.
"We are going to have to do something about it. I'm not happy with the way that local authorities are fulfilling their responsibilities in that area," he said.
"I have asked my department to produce guidelines over the autumn period."
He said the anomaly between the register and those eligible to vote suggested many voters were registered more than once.
"In some cases, those were people who have deliberately registered in two places, like students attending college away from home.
"(But) it seems to be that the majority of those 300,000, they are errors. There are people who have died or who have moved away.
"In very many cases, there are multiple entries. That's just carelessness. That can easily be checked."
Mr Roche dismissed the suggestion that fraudulent registration may have taken place. "It may be part of it. I'm not sure it's the greatest part, if it exists at all."
Mr Roche said some local authorities have been careless about their registers, but the guidelines would resolve this.
It had been suggested that the names on the electoral rolls of local authorities could be cross-checked centrally using individuals' PPS (social security) numbers.
However, Mr Roche said there would be difficulties posed by using PPS numbers as a safeguard against double-registration and fraud.
"There are privacy issues," Mr Roche said. "PPS numbers were created for social welfare and Revenue. They were not created for this.
"If we are going to use the PPS, you would have to have an IT connection in every council office to the PPS registers (in Revenue and in the Department of Social and Family Affairs). That raises questions of data protection," he said.
The director of the General Council of County Councils, Liam Kenny, said yesterday the issue was not that simple, and indicated the criticism of local authorities was harsh.
"I accept that work needs to be done to tighten up the system, but the practicalities of maintaining a register in an era of a very fluid population, with many people regularly moving, is a difficult business, no matter who does it."
The time was gone when "everybody knew everybody" in a community, he said. "We're living in an era of gated apartment blocks and lots of rental accommodation. Whether the register is managed at a central or local level, it's a very hard challenge.
He may be the Terry Wogan of Irish politics, often smooth and smug, but Environment Minister Dick Roche has a clear vision of his brief, writes Harry McGee.
THE interview is long over. You are looking at the reading on the recorder. Eek! An hour and 15 minutes of Dick Roche to transcribe! A mist of despondency descends. This is a marathon and you've hit the wall before you begin.
But a funny thing happened when listening back to the interview. Yes, sure, Roche is loquacious. Everybody knows that. Sometimes he's too smooth. Sometimes he sounds too smug. Sometimes he sells himself too much. But hearing it makes for astonishingly easy listening. You have fiddled with the Government dial and accidentally tuned into the Terry Wogan of Irish politics. His enthusiasm pulses out. He is so evangelical, so interested, and is committed to the context of his brief, in a way that reminds you a lot of Micheál Martin.
Roche is just shy of a year in Environment after his belated promotion to senior Cabinet. He certainly hasn't dawdled. And he does have a clear vision of his brief. It's not that far removed from his predecessor, Martin Cullen, despite all the polish. There's a lot of identifiably Fianna Fáil stuff.
Incineration (but not in my Wicklow back yard). Rural housing. The barter of State-owned sites for social housing. The Critical Infrastructure Bill. The ditching of carbon tax.
But he has played hard ball with under-performing local authorities, has made big strides with pay-for-waste initiatives and has finally resolved the IKEA question.
No policy is as identifiably Fianna Fáil as rural housing. Roche denies flatly that his guidelines were motivated by narrow party gain.
"It is a fact that a high proportion of Irish people still live outside urban areas. We have a countryside that did have a substantial rural population. We were left with a very unbalanced situation. Unfortunately, in a huge number of cases that I have become aware of, there were inflexibilities in the planning system.
"Those involved in a local community can build their home in the area. No harm is done by giving them planning permission for a well-sited house that meets the requirements for effluent treatment and traffic conditions."
But haven't councillors played fast and loose with planning laws before? What about the house for the nephew, that had a 'for sale' sign up before the scaffold came down?
"This is not a charter for despoiling the countryside. It's selective and focused. People will have to show they have long-term connections with an area," he counters.
You mention 10-year inurement clauses in some local authority areas, and go on to point out their absence in others. The inconsistency in performance of councils is a strong area for Roche who has been bullish about exposing under-performing authorities. In a double whammy move, he takes a swipe against the poor housing records of some local authority.
But it's a prelude for a bigger haymaker directed at Labour's environment spokesperson Eamon Gilmore.
"Dun Laoghaire Rathdown has one of the worst output records (for housing). Eamon Gilmore comes into the Dáil daily and wrings his hands like a hypocrite about housing. If I were in the Labour Party, I would be demanding that my local councillors deliver."
But Gilmore is no longer a member of a local authority. Can't he say you are the minister and what are you doing about it?
"Well, what I am not doing," he retorts, "is coming into the Dáil and protesting like a hypocrite every day.
"I will be putting pressure on the local authorities and telling them they have to deliver. Again, Eamon Gilmore will say there's far too much central government interference.
"But when the local authorities are given the resources to build houses, they should build houses. They should not be dodging and ducking and not building houses."
A couple of feathers are smoothed back into position before he moves onto his next quarry, the electoral register.
"The register is an appalling mess," he pronounces. "Every practising politician will tell you that. It has been tolerated for at least a generation.
"We are going to have to do something about it. I'm not happy with the way that local authorities are fulfilling their responsibilities in that area.
"I'm going to work on guidelines and I have asked my department to produce guidelines over the autumn period."
The academic that Roche used to be emerges: "If you add up all the voting registers that were extant at the time of the general election, there were 3.037 million voters on all those registers. But there are only about 2.71 million people eligible to vote in this country. That suggests that there are 300,000 over-registered places.
"Now in some cases, that was people who have deliberately registered in two places, like students attending college away from home. It seems to be that the majority of those 300,000, they are errors. There are people who have died or who have moved away. In very many cases, there are multiple entries. That's just carelessness. That can easily be checked. That is not being done."
On the thorny subject of elections, are the much maligned electronic voting machines going to make their debut in 2007? Roche gives a long discourse on the pros and cons of the system, summing it up with his view that electronic voting "can be better than pencil and paper".
In long recounts using the old method, did they get it right? he asks. He instances Dick Spring's slither-margin of four votes in 1987. "Who could put their hand on the Bible and say that it was right?" And in a similarly narrow battle between Ben Briscoe and Eric Byrne in 1992: "The ballot papers were reduced to practical pulp. They were literally decaying."
That is one of the reasons he gives for being against a paper audit trail: "You can't get precision in paper system."
Shortly after he came into office, Roche scrapped Cullen's proposals for a Critical Infrastructure Bill and replaced it with a proposal whereby An Bord Pleanála would determine applications for major projects (like incinerators) at first instance and not on appeal.
The debate has been well ventilated. There is one new departure. Roche now wants to suggest changes in the court system to streamline the process further.
"I don't want to start prescribing. But I would like to see a division of the High Court dedicated to planning issues along the same lines as the commercial court which has been very successful," he says.
"We are a very litigious nation. We should look at the model of commercial court and replicate that in planning."
In that very area, what is his opinion on Cullen's recent broadside against those who bring court challenges against road projects? You sense a re-ruffling of feathers. Wait for it.
"There have been people in this country, politicians, and I would specifically instance the Green Party, who have used and abused the planning system to give them a political platform.
"The classic example of that was the N11, the Glen of the Downs. The road did not progress for two and a half years and it over-ran its budget by up to €40 million.
"For no reason whatsoever, the Green Party came out and threw their weight behind the protest nationally. They cost the taxpayers tens of millions. They delayed the road project. The public were deliberately misinformed that all the tress were to be cut down. To be blunt about it, that was lies."
Strong stuff. But in a democratic society like ours, one that is protected by a Constitution, are people not fully within their rights to take such challenges? Is his infrastructure bill not foreclosing those rights?
"People will still be able to go to the court," he maintains. "They will not be able to go to the court in a way that is abusive.
"It's a bit perverse that somebody who has not participated in the planning system can come along at the 11th hour and abuse a very good court system."
He comes out with the Government line that a FG-Labour-Green axis would be confused, split, cumbersome. But FF had no difficulty jumping into bed with Labour and then the PDs. Ah, he replies, FF are centrist.
Roche uses a classic Rochism when defending the Government of charges of arrogance.
"If you throw an appellation that you believe to be muck it will stick.
"I do not understand how it can be logical to describe a government whose leader still goes out and knocks on doors as a government that is distant from people on the street."
Yep, long on words. But not all that short on interest.