AN Irish Water request for PPS numbers was strongly opposed by staff at the Department of Social Protection, who raised concerns about their responsibilities under official secrets laws.
Correspondence released under the Freedom of Information Act has revealed how the hated utility requested a "data dump" from the department.
This would involve the department handing over its database of PPS numbers to the semi-state body, including information on children for whom child benefit was paid.
But there were serious concerns over data protection and other laws protecting privacy.
There was widespread public outrage about the prospect of handing over PPS numbers to Irish Water.
Last month, the Government eventually decided to abolish the necessity to hand over the details, as part of a package that attempted to quell public fury.
Prior to this, the water company had second source PPS information, so it could be verified after individuals voluntarily sent their details and those of their children.
Irish Water claimed that it needed the details so that allowances for water charges could be allocated.
But secretary general of the Department of Social Protection Niamh O'Donoghue put her foot down and said that Irish Water would "get nothing" until it wrote to her formally, The Irish Times is reporting today.
Irish Water only wrote to Ms O'Donoghue on September 18, which was weeks after it first started sending registration packs to people's homes.
An internal departmental memo on the issue in late October shed light on the view of its officials on how Irish Water was conducting itself.
It said that Irish Water had given the issue "little thought, so this discussion will go on for a wee while", according to the documents.
"We are making progress as you will see, but DSP objective is to protect its data, its reputation and minimise its commitment while being supportive to IW as directed in the Government decision [on water charges]," it added.
In one email, concern was expressed that the department could be blamed for shortfalls in the performance of Irish Water.
The department set out that it was "pushing back strongly" against Irish Water's request that it verify a customer was a recipient of child benefit.
Officials were also concerned they could end up determining eligibility for water allowances, which was "neither intended by the Government decision nor acceptable" to the department, according to the documents.