The first Irish Water bills are due to begin arriving through letterboxes from today.
The company has already warned that they are likely to contain errors and incorrect information.
They're urging those affected to contact them, and have hired more than 700 customer service staff to take calls on the company's helplines.
A total of 1.7 million bills are being issued, despite Irish Water saying it will only have 1.5 million customers. The remainder will be sent to people such as customers of group water schemes, who are not Irish Water customers.
Customers have two weeks from the date their bill is issued to pay - but no penalties will accrue until a full year after the first bill goes unpaid.
Opposition TDs are telling people not to pay - and Sinn Fein has published a bill which would abolish Irish Water entirely, saying it would be its first act in a new government.
Our political correspondent Gavan Reilly filed this report for Today FM's National Lunchtime News:
