The Department of Social Protection has estimated that the cost of administering the €100 water conservation grant for this year will be almost a quarter of a million euro despite the fact that another round of payments is unlikely to be made in 2016.
According to documents from the department the administration and payment of the grant is a 'significant project'.
It says €5.7m was spent on administrative costs up to the end of 2015 on processing the payments.
It says in the region of €210,000 will be needed for administration in 2016.
Just under €89m in grants had been issued to 888,000 households up until February this year.
In a statement, the department said the 2016 costs relate to legitimate applications for the grant which may have been late or delayed due to problems with bank account details.
It also says some costs, which it describes as small, are incurred in maintaining and operating the grant IT system and website.