Irish Water has said 1.32million households have registered with them as the deadline for availing of the €100 water conservation grant looms today.
The utility said three-in-10 households in the country could miss out on the grant by not registering by today.
It is estimated there are around 1.7 million households in the country but not all of them would be customers of Irish Water if they are using group schemes or wells.
But Irish Water has stressed that every household across the country is eligible for the government grant regardless of whether they are a customer or not.
The grant will be paid by the Department of Social Protection on behalf of the Department of Environment, community and Local Government to householders who register. The €100 will be paid in September.
Irish Water would not comment on how many customers have paid their bills since they were issued in recent weeks.
Anti-austerity groups and anti water-charge lobbies have called for mass non-payment of the controversial charge in the hope that it will lead to the demise of the utility.
Meanwhile, the Government was accused this week of 'sneaking in' changes to a draft law giving effect to penalties for people refusing to pay their water charges.
The penalty clauses could block the sale of a house, including council tenant purchases, until all water charges are paid up.