A "seismic" process is under way at Irish Water to delete all Personal Public Service (PPS) numbers supplied to the company, Minister for the Environment Alan Kelly told the Dáil.

He said that some time “in the medium-term”, Irish Water should attend the Oireachtas Environment Committee to confirm that the process of deleting PPS numbers is complete.

He would then call on the Data Protection Commissioner to audit Irish Water and confirm no numbers had been retained.

Mr Kelly was speaking during a debate on the Water Services Bill as he refused the inclusion in the legislation of amendments from Independent Catherine Murphy that within four weeks of implementation of the Bill, all PPS numbers should be deleted and that a report from the Data Protection Commissioner should confirm deletion.

He said Irish Water had started work on removing PPS numbers and it was being done in accordance with a protocol the company had developed in conjunction with the commissioner. The Minister said the information about the process and a detailed summary of it is available on Irish Water’s website.

Mr Kelly described the process of deleting the numbers as “quite seismic, considering the number of forms”. It included the redaction of scanned images of applications forms and then the systematic destruction of the paper forms. They also had to clean up data not just from paper applications, but from voicemails and online.

It was “very easy to quickly remove a large bulk of PPS numbers – I am pretty sure I could do it myself”.

However, the process to guarantee that 100 per cent have been removed “requires a more sophisticated approach”. He said it would take several months to complete the process.