Householders are liable for water charges bills up to the end of March, Irish Water has said.
The statement follows inquiries by one customer who received a bill on May 10th.
Geraldine Hennessy said she was puzzled when she received a bill after the Government announced that water charges would be suspended for nine months.
When she rang up Irish Water to inquire as to whether or not she should pay her bill, she was told that they had received "no formal directive" from the Government on the subject.
Ms Hennessy, who lives in Donnybrook in Dublin, said she had paid all her water bills to date and was prepared to pay the latest one, which was €40 for the first quarter of 2016.
“I don’t have a problem paying for my water. It is an investment really to upgrade the system, but I don’t want to pay Irish Water €40 only to be told a week later that water rates are gone.
“I don’t see the logic of giving back money to people because, when they paid it, it was the law of the land.”
A spokeswoman for Irish Water said the Government announced the suspension of water charges with effect from the end of March 2016, but charges apply up to that time.
The spokeswoman said: “Irish Water is currently issuing bills to customers for services provided in January, February and March of this year. Billing will be completed in the first week in June.
“Irish Water customers remain liable for balances due on any bills issued for services provided up to the end of March 2016 and Irish Water continues to accept payment and to deal with any billing queries in relation to outstanding balances.”