Irish Water today advised landlords to pass on details of their tenants to the utility company.
Residential landlords who fear they will be asked to pay water charges on behalf of tenants are seeking a meeting with the Environment Minister over the issue.
Tenants have been urged to register their details with Irish Water, in advance of the first residential bills being sent to households next month.
However, the company said that there has been a low uptake across the rental sector - with only around half of those who live in rented accommodation registering.
By law, the occupier of a property is liable to pay domestic water charges, unless they can prove they do not live at the address.
Irish Water's Elizabeth Arnett said that landlords can pass the details of their tenants to the utility company.
"So in the instance if an occupier hasn't registered their details, the landlord can now contact us and say: 'Look, I do own that property, it is connected to public water services, but it's not me that lives there, it's so-and-so'," she said.
"The only thing we're looking for is the name. And then we will then contact the occupier and inform them that their name has been given to us, and invite them to register directly."