Households who have not yet registered with Irish Water have until midnight tonight to submit their details, however they will still be able to avail of the €100 water conservation grant if they miss the deadline.
The Department of the Environment confirmed that there is no deadline in place for households to apply for the €100 grant.
Irish Water have said 1.1m households have registered with them so far.
That means 58% of the total customer base have registered.
Irish Water added homeowners will be charged the default rate of €260, if they do not register.
Households with two adults, who take water in and require waste water to be taken out - will face the €260 charge in April whether they register or not.